Vulnerability-Lookup

GHSA-PGRF-4654-3GQ8

Vulnerability from github – Published: 2026-08-20 18:43 – Updated: 2026-08-20 18:43

Summary

netty-incubator-codec-ohttp: Binary HTTP parser unchecked varint length overflow causes decoder crash

Details

Summary

io.netty.incubator:netty-incubator-codec-bhttp uses attacker-controlled Binary HTTP variable-length integers as long values but accumulates them into int offsets. Large valid varint lengths wrap the internal offset negative, leading to unchecked ArrayIndexOutOfBoundsException / IndexOutOfBoundsException from a tiny malformed BHTTP payload. A remote peer can trigger connection-level denial of service in applications that expose BinaryHttpParser / BinaryHttpDecoder to untrusted input.

Details

In codec-bhttp/src/main/java/io/netty/incubator/codec/bhttp/BinaryHttpParser.java, several parser paths store cumulative byte offsets in int sumBytes and then add attacker-controlled long lengths using compound assignment. In Java, int += long narrows the result back to int, so a length such as 2^31 wraps sumBytes negative.

Primary request-control-data path:

readRequestHead(...) declares int sumBytes = 0 at BinaryHttpParser.java:386.
It reads methodLength as a long at BinaryHttpParser.java:394.
It performs sumBytes += methodLength at BinaryHttpParser.java:395, narrowing the result to int.
If methodLength is 2^31, sumBytes wraps negative and bypasses if (sumBytes >= in.readableBytes()) return null at BinaryHttpParser.java:396-398.
The parser then computes schemeLengthIdx = in.readerIndex() + sumBytes and calls in.getByte(schemeLengthIdx) at BinaryHttpParser.java:401-402, producing a negative index exception.

The same pattern is present in header parsing:

readFieldLine(...) uses int sumBytes and adds long nameLength / long valueLength at BinaryHttpParser.java:659-680.
valueLengthIdx = nameIdx + (int) nameLength at BinaryHttpParser.java:674 can also overflow.

getIndeterminateLength(...) similarly uses int sumBytes and long possibleTerminator at BinaryHttpParser.java:544-553.

Proof of concept

Safe local verification performed in this repository. After compiling codec-bhttp, the following minimal verifier uses a 15-byte payload:

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.incubator.codec.bhttp.BinaryHttpParser;

public final class VerifyBhttpOverflow {
  public static void main(String[] args) {
    byte[] payload = new byte[] {
      0x00, (byte)0xc0, 0x00, 0x00, 0x00, (byte)0x80, 0x00, 0x00, 0x00,
      0x47, 0x45, 0x54, 0x58, 0x58, 0x58
    };
    ByteBuf input = Unpooled.wrappedBuffer(payload);
    try {
      new BinaryHttpParser(8192).parse(input, false);
      System.out.println("returned");
    } catch (Throwable t) {
      System.out.println(t.getClass().getName());
      System.out.println(t.getMessage());
    }
  }
}

Payload interpretation:

00: known-length request frame indicator.
c000000080000000: valid 8-byte varint encoding of 0x80000000 (2^31) as the method length.
474554585858: a few dummy bytes so the parser proceeds far enough to compute the next index.

Observed result:

java.lang.ArrayIndexOutOfBoundsException
Index -2147483639 out of bounds for length 15

The parser should reject the malformed/incomplete message with a controlled decoder exception or return null awaiting more bytes; it should not allow integer wraparound to reach unchecked buffer indexing.

Impact

A remote peer can trigger an unchecked exception in the Binary HTTP decoder using a tiny payload. In typical Netty pipelines this closes or fails the affected channel. Depending on application-level exception handling, repeated payloads can cause sustained denial of service for exposed BHTTP endpoints. No memory corruption or information disclosure was observed because the failure occurs in Java/Netty bounds checks.

Suggested remediation

Use long for all cumulative byte counts derived from protocol lengths.
Before converting any protocol length to int, verify it is non-negative, no larger than Integer.MAX_VALUE, and no larger than available readable bytes and configured limits.
Replace sumBytes >= in.readableBytes() checks with precise checked arithmetic that permits exact-boundary complete fields but rejects impossible lengths.
Throw a controlled CorruptedFrameException / TooLongFrameException for invalid or unsupported lengths.
Add regression tests for 8-byte varint lengths at and above Integer.MAX_VALUE in request control data, response control data, known and indeterminate field sections, and field lines.

References

codec-bhttp/src/main/java/io/netty/incubator/codec/bhttp/BinaryHttpParser.java:386-402
codec-bhttp/src/main/java/io/netty/incubator/codec/bhttp/BinaryHttpParser.java:659-680
codec-bhttp/src/main/java/io/netty/incubator/codec/bhttp/BinaryHttpParser.java:544-553
RFC 9292: Binary Representation of HTTP Messages
RFC 9000 variable-length integer encoding

Severity

5.3 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.0.22.Final"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "io.netty.incubator:netty-incubator-codec-bhttp"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.0.23.Final"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-61799"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-190",
      "CWE-248",
      "CWE-681"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-20T18:43:21Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\n\n`io.netty.incubator:netty-incubator-codec-bhttp` uses attacker-controlled Binary HTTP variable-length integers as `long` values but accumulates them into `int` offsets. Large valid varint lengths wrap the internal offset negative, leading to unchecked `ArrayIndexOutOfBoundsException` / `IndexOutOfBoundsException` from a tiny malformed BHTTP payload. A remote peer can trigger connection-level denial of service in applications that expose `BinaryHttpParser` / `BinaryHttpDecoder` to untrusted input.\n\n## Details\n\nIn `codec-bhttp/src/main/java/io/netty/incubator/codec/bhttp/BinaryHttpParser.java`, several parser paths store cumulative byte offsets in `int sumBytes` and then add attacker-controlled `long` lengths using compound assignment. In Java, `int += long` narrows the result back to `int`, so a length such as `2^31` wraps `sumBytes` negative.\n\nPrimary request-control-data path:\n\n- `readRequestHead(...)` declares `int sumBytes = 0` at `BinaryHttpParser.java:386`.\n- It reads `methodLength` as a `long` at `BinaryHttpParser.java:394`.\n- It performs `sumBytes += methodLength` at `BinaryHttpParser.java:395`, narrowing the result to `int`.\n- If `methodLength` is `2^31`, `sumBytes` wraps negative and bypasses `if (sumBytes \u003e= in.readableBytes()) return null` at `BinaryHttpParser.java:396-398`.\n- The parser then computes `schemeLengthIdx = in.readerIndex() + sumBytes` and calls `in.getByte(schemeLengthIdx)` at `BinaryHttpParser.java:401-402`, producing a negative index exception.\n\nThe same pattern is present in header parsing:\n\n- `readFieldLine(...)` uses `int sumBytes` and adds `long nameLength` / `long valueLength` at `BinaryHttpParser.java:659-680`.\n- `valueLengthIdx = nameIdx + (int) nameLength` at `BinaryHttpParser.java:674` can also overflow.\n\n`getIndeterminateLength(...)` similarly uses `int sumBytes` and `long possibleTerminator` at `BinaryHttpParser.java:544-553`.\n\n## Proof of concept\n\nSafe local verification performed in this repository. After compiling `codec-bhttp`, the following minimal verifier uses a 15-byte payload:\n\n```java\nimport io.netty.buffer.ByteBuf;\nimport io.netty.buffer.Unpooled;\nimport io.netty.incubator.codec.bhttp.BinaryHttpParser;\n\npublic final class VerifyBhttpOverflow {\n  public static void main(String[] args) {\n    byte[] payload = new byte[] {\n      0x00, (byte)0xc0, 0x00, 0x00, 0x00, (byte)0x80, 0x00, 0x00, 0x00,\n      0x47, 0x45, 0x54, 0x58, 0x58, 0x58\n    };\n    ByteBuf input = Unpooled.wrappedBuffer(payload);\n    try {\n      new BinaryHttpParser(8192).parse(input, false);\n      System.out.println(\"returned\");\n    } catch (Throwable t) {\n      System.out.println(t.getClass().getName());\n      System.out.println(t.getMessage());\n    }\n  }\n}\n```\n\nPayload interpretation:\n\n- `00`: known-length request frame indicator.\n- `c000000080000000`: valid 8-byte varint encoding of `0x80000000` (`2^31`) as the method length.\n- `474554585858`: a few dummy bytes so the parser proceeds far enough to compute the next index.\n\nObserved result:\n\n```text\njava.lang.ArrayIndexOutOfBoundsException\nIndex -2147483639 out of bounds for length 15\n```\n\nThe parser should reject the malformed/incomplete message with a controlled decoder exception or return `null` awaiting more bytes; it should not allow integer wraparound to reach unchecked buffer indexing.\n\n## Impact\n\nA remote peer can trigger an unchecked exception in the Binary HTTP decoder using a tiny payload. In typical Netty pipelines this closes or fails the affected channel. Depending on application-level exception handling, repeated payloads can cause sustained denial of service for exposed BHTTP endpoints. No memory corruption or information disclosure was observed because the failure occurs in Java/Netty bounds checks.\n\n## Suggested remediation\n\n- Use `long` for all cumulative byte counts derived from protocol lengths.\n- Before converting any protocol length to `int`, verify it is non-negative, no larger than `Integer.MAX_VALUE`, and no larger than available readable bytes and configured limits.\n- Replace `sumBytes \u003e= in.readableBytes()` checks with precise checked arithmetic that permits exact-boundary complete fields but rejects impossible lengths.\n- Throw a controlled `CorruptedFrameException` / `TooLongFrameException` for invalid or unsupported lengths.\n- Add regression tests for 8-byte varint lengths at and above `Integer.MAX_VALUE` in request control data, response control data, known and indeterminate field sections, and field lines.\n\n## References\n\n- `codec-bhttp/src/main/java/io/netty/incubator/codec/bhttp/BinaryHttpParser.java:386-402`\n- `codec-bhttp/src/main/java/io/netty/incubator/codec/bhttp/BinaryHttpParser.java:659-680`\n- `codec-bhttp/src/main/java/io/netty/incubator/codec/bhttp/BinaryHttpParser.java:544-553`\n- RFC 9292: Binary Representation of HTTP Messages\n- RFC 9000 variable-length integer encoding",
  "id": "GHSA-pgrf-4654-3gq8",
  "modified": "2026-08-20T18:43:21Z",
  "published": "2026-08-20T18:43:21Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/netty/netty-incubator-codec-ohttp/security/advisories/GHSA-pgrf-4654-3gq8"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/netty/netty-incubator-codec-ohttp"
    },
    {
      "type": "WEB",
      "url": "https://github.com/netty/netty-incubator-codec-ohttp/releases/tag/netty-incubator-codec-parent-ohttp-0.0.23.Final"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "netty-incubator-codec-ohttp: Binary HTTP parser unchecked varint length overflow causes decoder crash"
}

Sightings

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Nomenclature

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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.

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GHSA-PGRF-4654-3GQ8

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