Vulnerability-Lookup

CVE-2026-2391 (GCVE-0-2026-2391)

Vulnerability from cvelistv5 – Published: 2026-02-12 04:39 – Updated: 2026-02-12 17:32

Title

qs's arrayLimit bypass in comma parsing allows denial of service

Summary

### Summary The `arrayLimit` option in qs does not enforce limits for comma-separated values when `comma: true` is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of the array limit enforcement, similar to the bracket notation bypass addressed in GHSA-6rw7-vpxm-498p (CVE-2025-15284). ### Details When the `comma` option is set to `true` (not the default, but configurable in applications), qs allows parsing comma-separated strings as arrays (e.g., `?param=a,b,c` becomes `['a', 'b', 'c']`). However, the limit check for `arrayLimit` (default: 20) and the optional throwOnLimitExceeded occur after the comma-handling logic in `parseArrayValue`, enabling a bypass. This permits creation of arbitrarily large arrays from a single parameter, leading to excessive memory allocation. **Vulnerable code** (lib/parse.js: lines ~40-50): ```js if (val && typeof val === 'string' && options.comma && val.indexOf(',') > -1) { return val.split(','); } if (options.throwOnLimitExceeded && currentArrayLength >= options.arrayLimit) { throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.'); } return val; ``` The `split(',')` returns the array immediately, skipping the subsequent limit check. Downstream merging via `utils.combine` does not prevent allocation, even if it marks overflows for sparse arrays.This discrepancy allows attackers to send a single parameter with millions of commas (e.g., `?param=,,,,,,,,...`), allocating massive arrays in memory without triggering limits. It bypasses the intent of `arrayLimit`, which is enforced correctly for indexed (`a[0]=`) and bracket (`a[]=`) notations (the latter fixed in v6.14.1 per GHSA-6rw7-vpxm-498p). ### PoC **Test 1 - Basic bypass:** ``` npm install qs ``` ```js const qs = require('qs'); const payload = 'a=' + ','.repeat(25); // 26 elements after split (bypasses arrayLimit: 5) const options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true }; try { const result = qs.parse(payload, options); console.log(result.a.length); // Outputs: 26 (bypass successful) } catch (e) { console.log('Limit enforced:', e.message); // Not thrown } ``` **Configuration:** - `comma: true` - `arrayLimit: 5` - `throwOnLimitExceeded: true` Expected: Throws "Array limit exceeded" error. Actual: Parses successfully, creating an array of length 26. ### Impact Denial of Service (DoS) via memory exhaustion.

Severity ?

6.3 (Medium)


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

3.7 (Low)


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

CWE

CWE-20 - Improper Input Validation

Assigner

harborist

References

URL

Tags

	https://github.com/ljharb/qs/security/advisories/…	vendor-advisory
	https://github.com/ljharb/qs/commit/f6a7abff1f13d…	patch

Impacted products

	Vendor	Product	Version
			Affected: 6.7.0 , ≤ 6.14.1 (semver)

Show details on NVD website

JSON

To clipboard

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              "value": "### Summary\u003cbr\u003eThe `arrayLimit` option in qs does not enforce limits for comma-separated values when `comma: true` is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of the array limit enforcement, similar to the bracket notation bypass addressed in GHSA-6rw7-vpxm-498p (CVE-2025-15284).\u003cbr\u003e\u003cbr\u003e### Details\u003cbr\u003eWhen the `comma` option is set to `true` (not the default, but configurable in applications), qs allows parsing comma-separated strings as arrays (e.g., `?param=a,b,c` becomes `[\u0027a\u0027, \u0027b\u0027, \u0027c\u0027]`). However, the limit check for `arrayLimit` (default: 20) and the optional throwOnLimitExceeded occur after the comma-handling logic in `parseArrayValue`, enabling a bypass. This permits creation of arbitrarily large arrays from a single parameter, leading to excessive memory allocation.\u003cbr\u003e\u003cbr\u003e**Vulnerable code** (lib/parse.js: lines ~40-50):\u003cbr\u003e```js\u003cbr\u003eif (val \u0026amp;\u0026amp; typeof val === \u0027string\u0027 \u0026amp;\u0026amp; options.comma \u0026amp;\u0026amp; val.indexOf(\u0027,\u0027) \u0026gt; -1) {\u003cbr\u003e\u0026nbsp; \u0026nbsp; return val.split(\u0027,\u0027);\u003cbr\u003e}\u003cbr\u003e\u003cbr\u003eif (options.throwOnLimitExceeded \u0026amp;\u0026amp; currentArrayLength \u0026gt;= options.arrayLimit) {\u003cbr\u003e\u0026nbsp; \u0026nbsp; throw new RangeError(\u0027Array limit exceeded. Only \u0027 + options.arrayLimit + \u0027 element\u0027 + (options.arrayLimit === 1 ? \u0027\u0027 : \u0027s\u0027) + \u0027 allowed in an array.\u0027);\u003cbr\u003e}\u003cbr\u003e\u003cbr\u003ereturn val;\u003cbr\u003e```\u003cbr\u003eThe `split(\u0027,\u0027)` returns the array immediately, skipping the subsequent limit check. Downstream merging via `utils.combine` does not prevent allocation, even if it marks overflows for sparse arrays.This discrepancy allows attackers to send a single parameter with millions of commas (e.g., `?param=,,,,,,,,...`), allocating massive arrays in memory without triggering limits. It bypasses the intent of `arrayLimit`, which is enforced correctly for indexed (`a[0]=`) and bracket (`a[]=`) notations (the latter fixed in v6.14.1 per GHSA-6rw7-vpxm-498p).\u003cbr\u003e\u003cbr\u003e### PoC\u003cbr\u003e**Test 1 - Basic bypass:**\u003cbr\u003e```\u003cbr\u003enpm install qs\u003cbr\u003e```\u003cbr\u003e\u003cbr\u003e```js\u003cbr\u003econst qs = require(\u0027qs\u0027);\u003cbr\u003e\u003cbr\u003econst payload = \u0027a=\u0027 + \u0027,\u0027.repeat(25);  // 26 elements after split (bypasses arrayLimit: 5)\u003cbr\u003econst options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true };\u003cbr\u003e\u003cbr\u003etry {\u003cbr\u003e\u0026nbsp; const result = qs.parse(payload, options);\u003cbr\u003e\u0026nbsp; console.log(result.a.length);  // Outputs: 26 (bypass successful)\u003cbr\u003e} catch (e) {\u003cbr\u003e\u0026nbsp; console.log(\u0027Limit enforced:\u0027, e.message);  // Not thrown\u003cbr\u003e}\u003cbr\u003e```\u003cbr\u003e**Configuration:**\u003cbr\u003e- `comma: true`\u003cbr\u003e- `arrayLimit: 5`\u003cbr\u003e- `throwOnLimitExceeded: true`\u003cbr\u003e\u003cbr\u003eExpected: Throws \"Array limit exceeded\" error.\u003cbr\u003eActual: Parses successfully, creating an array of length 26.\u003cbr\u003e\u003cbr\u003e\u003cbr\u003e### Impact\u003cbr\u003eDenial of Service (DoS) via memory exhaustion.\u003cbr\u003e"
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However, the limit check for `arrayLimit` (default: 20) and the optional throwOnLimitExceeded occur after the comma-handling logic in `parseArrayValue`, enabling a bypass. This permits creation of arbitrarily large arrays from a single parameter, leading to excessive memory allocation.\\n\\n**Vulnerable code** (lib/parse.js: lines ~40-50):\\n```js\\nif (val \u0026\u0026 typeof val === \u0027string\u0027 \u0026\u0026 options.comma \u0026\u0026 val.indexOf(\u0027,\u0027) \u003e -1) {\\n\u00a0 \u00a0 return val.split(\u0027,\u0027);\\n}\\n\\nif (options.throwOnLimitExceeded \u0026\u0026 currentArrayLength \u003e= options.arrayLimit) {\\n\u00a0 \u00a0 throw new RangeError(\u0027Array limit exceeded. Only \u0027 + options.arrayLimit + \u0027 element\u0027 + (options.arrayLimit === 1 ? \u0027\u0027 : \u0027s\u0027) + \u0027 allowed in an array.\u0027);\\n}\\n\\nreturn val;\\n```\\nThe `split(\u0027,\u0027)` returns the array immediately, skipping the subsequent limit check. Downstream merging via `utils.combine` does not prevent allocation, even if it marks overflows for sparse arrays.This discrepancy allows attackers to send a single parameter with millions of commas (e.g., `?param=,,,,,,,,...`), allocating massive arrays in memory without triggering limits. It bypasses the intent of `arrayLimit`, which is enforced correctly for indexed (`a[0]=`) and bracket (`a[]=`) notations (the latter fixed in v6.14.1 per GHSA-6rw7-vpxm-498p).\\n\\n### PoC\\n**Test 1 - Basic bypass:**\\n```\\nnpm install qs\\n```\\n\\n```js\\nconst qs = require(\u0027qs\u0027);\\n\\nconst payload = \u0027a=\u0027 + \u0027,\u0027.repeat(25);  // 26 elements after split (bypasses arrayLimit: 5)\\nconst options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true };\\n\\ntry {\\n\u00a0 const result = qs.parse(payload, options);\\n\u00a0 console.log(result.a.length);  // Outputs: 26 (bypass successful)\\n} catch (e) {\\n\u00a0 console.log(\u0027Limit enforced:\u0027, e.message);  // Not thrown\\n}\\n```\\n**Configuration:**\\n- `comma: true`\\n- `arrayLimit: 5`\\n- `throwOnLimitExceeded: true`\\n\\nExpected: Throws \\\"Array limit exceeded\\\" error.\\nActual: Parses successfully, creating an array of length 26.\\n\\n\\n### Impact\\nDenial of Service (DoS) via memory exhaustion.\"}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"7ffcee3d-2c14-4c3e-b844-86c6a321a158\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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\":6.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"PRESENT\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"LOW\",\"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\"}}],\"cvssMetricV31\":[{\"source\":\"7ffcee3d-2c14-4c3e-b844-86c6a321a158\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L\",\"baseScore\":3.7,\"baseSeverity\":\"LOW\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"LOW\"},\"exploitabilityScore\":2.2,\"impactScore\":1.4}]},\"weaknesses\":[{\"source\":\"7ffcee3d-2c14-4c3e-b844-86c6a321a158\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-20\"}]}],\"references\":[{\"url\":\"https://github.com/ljharb/qs/commit/f6a7abff1f13d644db9b05fe4f2c98ada6bf8482\",\"source\":\"7ffcee3d-2c14-4c3e-b844-86c6a321a158\"},{\"url\":\"https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883\",\"source\":\"7ffcee3d-2c14-4c3e-b844-86c6a321a158\"},{\"url\":\"https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883\",\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\"}]}}",
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      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-2391\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-02-12T15:00:21.359233Z\"}}}], \"references\": [{\"url\": \"https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-02-12T15:00:12.364Z\"}}], \"cna\": {\"title\": \"qs\u0027s arrayLimit bypass in comma parsing allows denial of service\", \"source\": {\"discovery\": \"UNKNOWN\"}, \"impacts\": [{\"capecId\": \"CAPEC-130\", \"descriptions\": [{\"lang\": \"en\", \"value\": \"CAPEC-130 Excessive Allocation\"}]}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"Safety\": \"NOT_DEFINED\", \"version\": \"4.0\", \"Recovery\": \"NOT_DEFINED\", \"baseScore\": 6.3, \"Automatable\": \"NOT_DEFINED\", \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"valueDensity\": \"NOT_DEFINED\", \"vectorString\": \"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N\", \"exploitMaturity\": \"NOT_DEFINED\", \"providerUrgency\": \"NOT_DEFINED\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"PRESENT\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"NONE\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"LOW\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"NONE\", \"vulnerabilityResponseEffort\": \"NOT_DEFINED\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}, {\"format\": \"CVSS\", \"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 3.7, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"LOW\", \"vectorString\": \"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"HIGH\", \"availabilityImpact\": \"LOW\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"repo\": \"https://github.com/ljharb/qs\", \"versions\": [{\"status\": \"affected\", \"version\": \"6.7.0\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.14.1\"}], \"packageName\": \"qs\", \"collectionURL\": \"https://npmjs.com/qs\", \"defaultStatus\": \"unaffected\"}], \"references\": [{\"url\": \"https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883\", \"tags\": [\"vendor-advisory\"]}, {\"url\": \"https://github.com/ljharb/qs/commit/f6a7abff1f13d644db9b05fe4f2c98ada6bf8482\", \"tags\": [\"patch\"]}], \"x_generator\": {\"engine\": \"Vulnogram 0.5.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"### Summary\\nThe `arrayLimit` option in qs does not enforce limits for comma-separated values when `comma: true` is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of the array limit enforcement, similar to the bracket notation bypass addressed in GHSA-6rw7-vpxm-498p (CVE-2025-15284).\\n\\n### Details\\nWhen the `comma` option is set to `true` (not the default, but configurable in applications), qs allows parsing comma-separated strings as arrays (e.g., `?param=a,b,c` becomes `[\u0027a\u0027, \u0027b\u0027, \u0027c\u0027]`). However, the limit check for `arrayLimit` (default: 20) and the optional throwOnLimitExceeded occur after the comma-handling logic in `parseArrayValue`, enabling a bypass. This permits creation of arbitrarily large arrays from a single parameter, leading to excessive memory allocation.\\n\\n**Vulnerable code** (lib/parse.js: lines ~40-50):\\n```js\\nif (val \u0026\u0026 typeof val === \u0027string\u0027 \u0026\u0026 options.comma \u0026\u0026 val.indexOf(\u0027,\u0027) \u003e -1) {\\n\\u00a0 \\u00a0 return val.split(\u0027,\u0027);\\n}\\n\\nif (options.throwOnLimitExceeded \u0026\u0026 currentArrayLength \u003e= options.arrayLimit) {\\n\\u00a0 \\u00a0 throw new RangeError(\u0027Array limit exceeded. Only \u0027 + options.arrayLimit + \u0027 element\u0027 + (options.arrayLimit === 1 ? \u0027\u0027 : \u0027s\u0027) + \u0027 allowed in an array.\u0027);\\n}\\n\\nreturn val;\\n```\\nThe `split(\u0027,\u0027)` returns the array immediately, skipping the subsequent limit check. Downstream merging via `utils.combine` does not prevent allocation, even if it marks overflows for sparse arrays.This discrepancy allows attackers to send a single parameter with millions of commas (e.g., `?param=,,,,,,,,...`), allocating massive arrays in memory without triggering limits. It bypasses the intent of `arrayLimit`, which is enforced correctly for indexed (`a[0]=`) and bracket (`a[]=`) notations (the latter fixed in v6.14.1 per GHSA-6rw7-vpxm-498p).\\n\\n### PoC\\n**Test 1 - Basic bypass:**\\n```\\nnpm install qs\\n```\\n\\n```js\\nconst qs = require(\u0027qs\u0027);\\n\\nconst payload = \u0027a=\u0027 + \u0027,\u0027.repeat(25);  // 26 elements after split (bypasses arrayLimit: 5)\\nconst options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true };\\n\\ntry {\\n\\u00a0 const result = qs.parse(payload, options);\\n\\u00a0 console.log(result.a.length);  // Outputs: 26 (bypass successful)\\n} catch (e) {\\n\\u00a0 console.log(\u0027Limit enforced:\u0027, e.message);  // Not thrown\\n}\\n```\\n**Configuration:**\\n- `comma: true`\\n- `arrayLimit: 5`\\n- `throwOnLimitExceeded: true`\\n\\nExpected: Throws \\\"Array limit exceeded\\\" error.\\nActual: Parses successfully, creating an array of length 26.\\n\\n\\n### Impact\\nDenial of Service (DoS) via memory exhaustion.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"### Summary\u003cbr\u003eThe `arrayLimit` option in qs does not enforce limits for comma-separated values when `comma: true` is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of the array limit enforcement, similar to the bracket notation bypass addressed in GHSA-6rw7-vpxm-498p (CVE-2025-15284).\u003cbr\u003e\u003cbr\u003e### Details\u003cbr\u003eWhen the `comma` option is set to `true` (not the default, but configurable in applications), qs allows parsing comma-separated strings as arrays (e.g., `?param=a,b,c` becomes `[\u0027a\u0027, \u0027b\u0027, \u0027c\u0027]`). However, the limit check for `arrayLimit` (default: 20) and the optional throwOnLimitExceeded occur after the comma-handling logic in `parseArrayValue`, enabling a bypass. This permits creation of arbitrarily large arrays from a single parameter, leading to excessive memory allocation.\u003cbr\u003e\u003cbr\u003e**Vulnerable code** (lib/parse.js: lines ~40-50):\u003cbr\u003e```js\u003cbr\u003eif (val \u0026amp;\u0026amp; typeof val === \u0027string\u0027 \u0026amp;\u0026amp; options.comma \u0026amp;\u0026amp; val.indexOf(\u0027,\u0027) \u0026gt; -1) {\u003cbr\u003e\u0026nbsp; \u0026nbsp; return val.split(\u0027,\u0027);\u003cbr\u003e}\u003cbr\u003e\u003cbr\u003eif (options.throwOnLimitExceeded \u0026amp;\u0026amp; currentArrayLength \u0026gt;= options.arrayLimit) {\u003cbr\u003e\u0026nbsp; \u0026nbsp; throw new RangeError(\u0027Array limit exceeded. Only \u0027 + options.arrayLimit + \u0027 element\u0027 + (options.arrayLimit === 1 ? \u0027\u0027 : \u0027s\u0027) + \u0027 allowed in an array.\u0027);\u003cbr\u003e}\u003cbr\u003e\u003cbr\u003ereturn val;\u003cbr\u003e```\u003cbr\u003eThe `split(\u0027,\u0027)` returns the array immediately, skipping the subsequent limit check. Downstream merging via `utils.combine` does not prevent allocation, even if it marks overflows for sparse arrays.This discrepancy allows attackers to send a single parameter with millions of commas (e.g., `?param=,,,,,,,,...`), allocating massive arrays in memory without triggering limits. It bypasses the intent of `arrayLimit`, which is enforced correctly for indexed (`a[0]=`) and bracket (`a[]=`) notations (the latter fixed in v6.14.1 per GHSA-6rw7-vpxm-498p).\u003cbr\u003e\u003cbr\u003e### PoC\u003cbr\u003e**Test 1 - Basic bypass:**\u003cbr\u003e```\u003cbr\u003enpm install qs\u003cbr\u003e```\u003cbr\u003e\u003cbr\u003e```js\u003cbr\u003econst qs = require(\u0027qs\u0027);\u003cbr\u003e\u003cbr\u003econst payload = \u0027a=\u0027 + \u0027,\u0027.repeat(25);  // 26 elements after split (bypasses arrayLimit: 5)\u003cbr\u003econst options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true };\u003cbr\u003e\u003cbr\u003etry {\u003cbr\u003e\u0026nbsp; const result = qs.parse(payload, options);\u003cbr\u003e\u0026nbsp; console.log(result.a.length);  // Outputs: 26 (bypass successful)\u003cbr\u003e} catch (e) {\u003cbr\u003e\u0026nbsp; console.log(\u0027Limit enforced:\u0027, e.message);  // Not thrown\u003cbr\u003e}\u003cbr\u003e```\u003cbr\u003e**Configuration:**\u003cbr\u003e- `comma: true`\u003cbr\u003e- `arrayLimit: 5`\u003cbr\u003e- `throwOnLimitExceeded: true`\u003cbr\u003e\u003cbr\u003eExpected: Throws \\\"Array limit exceeded\\\" error.\u003cbr\u003eActual: Parses successfully, creating an array of length 26.\u003cbr\u003e\u003cbr\u003e\u003cbr\u003e### Impact\u003cbr\u003eDenial of Service (DoS) via memory exhaustion.\u003cbr\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-20\", \"description\": \"CWE-20 Improper Input Validation\"}]}], \"providerMetadata\": {\"orgId\": \"7ffcee3d-2c14-4c3e-b844-86c6a321a158\", \"shortName\": \"harborist\", \"dateUpdated\": \"2026-02-12T17:32:05.953Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-2391\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-02-12T17:32:05.953Z\", \"dateReserved\": \"2026-02-12T03:52:09.332Z\", \"assignerOrgId\": \"7ffcee3d-2c14-4c3e-b844-86c6a321a158\", \"datePublished\": \"2026-02-12T04:39:42.914Z\", \"assignerShortName\": \"harborist\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

GHSA-W7FW-MJWX-W883

Vulnerability from github – Published: 2026-02-12 17:04 – Updated: 2026-02-12 20:07

Summary

qs's arrayLimit bypass in comma parsing allows denial of service

Details

Summary

The arrayLimit option in qs does not enforce limits for comma-separated values when comma: true is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of the array limit enforcement, similar to the bracket notation bypass addressed in GHSA-6rw7-vpxm-498p (CVE-2025-15284).

Details

When the comma option is set to true (not the default, but configurable in applications), qs allows parsing comma-separated strings as arrays (e.g., ?param=a,b,c becomes ['a', 'b', 'c']). However, the limit check for arrayLimit (default: 20) and the optional throwOnLimitExceeded occur after the comma-handling logic in parseArrayValue, enabling a bypass. This permits creation of arbitrarily large arrays from a single parameter, leading to excessive memory allocation.

Vulnerable code (lib/parse.js: lines ~40-50):

if (val && typeof val === 'string' && options.comma && val.indexOf(',') > -1) {
    return val.split(',');
}

if (options.throwOnLimitExceeded && currentArrayLength >= options.arrayLimit) {
    throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.');
}

return val;

The split(',') returns the array immediately, skipping the subsequent limit check. Downstream merging via utils.combine does not prevent allocation, even if it marks overflows for sparse arrays.This discrepancy allows attackers to send a single parameter with millions of commas (e.g., ?param=,,,,,,,,...), allocating massive arrays in memory without triggering limits. It bypasses the intent of arrayLimit, which is enforced correctly for indexed (a[0]=) and bracket (a[]=) notations (the latter fixed in v6.14.1 per GHSA-6rw7-vpxm-498p).

PoC

Test 1 - Basic bypass:

npm install qs

const qs = require('qs');

const payload = 'a=' + ','.repeat(25);  // 26 elements after split (bypasses arrayLimit: 5)
const options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true };

try {
  const result = qs.parse(payload, options);
  console.log(result.a.length);  // Outputs: 26 (bypass successful)
} catch (e) {
  console.log('Limit enforced:', e.message);  // Not thrown
}

Configuration: - comma: true - arrayLimit: 5 - throwOnLimitExceeded: true

Expected: Throws "Array limit exceeded" error. Actual: Parses successfully, creating an array of length 26.

Impact

Denial of Service (DoS) via memory exhaustion.

Suggested Fix

Move the arrayLimit check before the comma split in parseArrayValue, and enforce it on the resulting array length. Use currentArrayLength (already calculated upstream) for consistency with bracket notation fixes.

Current code (lib/parse.js: lines ~40-50):

if (val && typeof val === 'string' && options.comma && val.indexOf(',') > -1) {
    return val.split(',');
}

if (options.throwOnLimitExceeded && currentArrayLength >= options.arrayLimit) {
    throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.');
}

return val;

Fixed code:

if (val && typeof val === 'string' && options.comma && val.indexOf(',') > -1) {
    const splitArray = val.split(',');
    if (splitArray.length > options.arrayLimit - currentArrayLength) {  // Check against remaining limit
        if (options.throwOnLimitExceeded) {
            throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.');
        } else {
            // Optionally convert to object or truncate, per README
            return splitArray.slice(0, options.arrayLimit - currentArrayLength);
        }
    }
    return splitArray;
}

if (options.throwOnLimitExceeded && currentArrayLength >= options.arrayLimit) {
    throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.');
}

return val;

This aligns behavior with indexed and bracket notations, reuses currentArrayLength, and respects throwOnLimitExceeded. Update README to note the consistent enforcement.

Severity ?

3.7 (Low)


                  
                    CVSS:3.1/AV:N/AC:H/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= 6.14.1"
      },
      "package": {
        "ecosystem": "npm",
        "name": "qs"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.14.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-2391"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-12T17:04:39Z",
    "nvd_published_at": "2026-02-12T05:17:11Z",
    "severity": "LOW"
  },
  "details": "### Summary\nThe `arrayLimit` option in qs does not enforce limits for comma-separated values when `comma: true` is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of the array limit enforcement, similar to the bracket notation bypass addressed in GHSA-6rw7-vpxm-498p (CVE-2025-15284).\n\n### Details\nWhen the `comma` option is set to `true` (not the default, but configurable in applications), qs allows parsing comma-separated strings as arrays (e.g., `?param=a,b,c` becomes `[\u0027a\u0027, \u0027b\u0027, \u0027c\u0027]`). However, the limit check for `arrayLimit` (default: 20) and the optional throwOnLimitExceeded occur after the comma-handling logic in `parseArrayValue`, enabling a bypass. This permits creation of arbitrarily large arrays from a single parameter, leading to excessive memory allocation.\n\n**Vulnerable code** (lib/parse.js: lines ~40-50):\n```js\nif (val \u0026\u0026 typeof val === \u0027string\u0027 \u0026\u0026 options.comma \u0026\u0026 val.indexOf(\u0027,\u0027) \u003e -1) {\n    return val.split(\u0027,\u0027);\n}\n\nif (options.throwOnLimitExceeded \u0026\u0026 currentArrayLength \u003e= options.arrayLimit) {\n    throw new RangeError(\u0027Array limit exceeded. Only \u0027 + options.arrayLimit + \u0027 element\u0027 + (options.arrayLimit === 1 ? \u0027\u0027 : \u0027s\u0027) + \u0027 allowed in an array.\u0027);\n}\n\nreturn val;\n```\nThe `split(\u0027,\u0027)` returns the array immediately, skipping the subsequent limit check. Downstream merging via `utils.combine` does not prevent allocation, even if it marks overflows for sparse arrays.This discrepancy allows attackers to send a single parameter with millions of commas (e.g., `?param=,,,,,,,,...`), allocating massive arrays in memory without triggering limits. It bypasses the intent of `arrayLimit`, which is enforced correctly for indexed (`a[0]=`) and bracket (`a[]=`) notations (the latter fixed in v6.14.1 per GHSA-6rw7-vpxm-498p).\n\n### PoC\n**Test 1 - Basic bypass:**\n```\nnpm install qs\n```\n\n```js\nconst qs = require(\u0027qs\u0027);\n\nconst payload = \u0027a=\u0027 + \u0027,\u0027.repeat(25);  // 26 elements after split (bypasses arrayLimit: 5)\nconst options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true };\n\ntry {\n  const result = qs.parse(payload, options);\n  console.log(result.a.length);  // Outputs: 26 (bypass successful)\n} catch (e) {\n  console.log(\u0027Limit enforced:\u0027, e.message);  // Not thrown\n}\n```\n**Configuration:**\n- `comma: true`\n- `arrayLimit: 5`\n- `throwOnLimitExceeded: true`\n\nExpected: Throws \"Array limit exceeded\" error.\nActual: Parses successfully, creating an array of length 26.\n\n\n### Impact\nDenial of Service (DoS) via memory exhaustion.\n\n### Suggested Fix\nMove the `arrayLimit` check before the comma split in `parseArrayValue`, and enforce it on the resulting array length. Use `currentArrayLength` (already calculated upstream) for consistency with bracket notation fixes.\n\n**Current code** (lib/parse.js: lines ~40-50):\n```js\nif (val \u0026\u0026 typeof val === \u0027string\u0027 \u0026\u0026 options.comma \u0026\u0026 val.indexOf(\u0027,\u0027) \u003e -1) {\n    return val.split(\u0027,\u0027);\n}\n\nif (options.throwOnLimitExceeded \u0026\u0026 currentArrayLength \u003e= options.arrayLimit) {\n    throw new RangeError(\u0027Array limit exceeded. Only \u0027 + options.arrayLimit + \u0027 element\u0027 + (options.arrayLimit === 1 ? \u0027\u0027 : \u0027s\u0027) + \u0027 allowed in an array.\u0027);\n}\n\nreturn val;\n```\n\n**Fixed code:**\n```js\nif (val \u0026\u0026 typeof val === \u0027string\u0027 \u0026\u0026 options.comma \u0026\u0026 val.indexOf(\u0027,\u0027) \u003e -1) {\n    const splitArray = val.split(\u0027,\u0027);\n    if (splitArray.length \u003e options.arrayLimit - currentArrayLength) {  // Check against remaining limit\n        if (options.throwOnLimitExceeded) {\n            throw new RangeError(\u0027Array limit exceeded. Only \u0027 + options.arrayLimit + \u0027 element\u0027 + (options.arrayLimit === 1 ? \u0027\u0027 : \u0027s\u0027) + \u0027 allowed in an array.\u0027);\n        } else {\n            // Optionally convert to object or truncate, per README\n            return splitArray.slice(0, options.arrayLimit - currentArrayLength);\n        }\n    }\n    return splitArray;\n}\n\nif (options.throwOnLimitExceeded \u0026\u0026 currentArrayLength \u003e= options.arrayLimit) {\n    throw new RangeError(\u0027Array limit exceeded. Only \u0027 + options.arrayLimit + \u0027 element\u0027 + (options.arrayLimit === 1 ? \u0027\u0027 : \u0027s\u0027) + \u0027 allowed in an array.\u0027);\n}\n\nreturn val;\n```\nThis aligns behavior with indexed and bracket notations, reuses `currentArrayLength`, and respects `throwOnLimitExceeded`. Update README to note the consistent enforcement.",
  "id": "GHSA-w7fw-mjwx-w883",
  "modified": "2026-02-12T20:07:59Z",
  "published": "2026-02-12T17:04:39Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-2391"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ljharb/qs/commit/f6a7abff1f13d644db9b05fe4f2c98ada6bf8482"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ljharb/qs"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "qs\u0027s arrayLimit bypass in comma parsing allows denial of service"
}

FKIE_CVE-2026-2391

Vulnerability from fkie_nvd - Published: 2026-02-12 05:17 - Updated: 2026-02-12 16:16

Severity ?

3.7 (Low) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Summary

References

	URL	Tags
	7ffcee3d-2c14-4c3e-b844-86c6a321a158	https://github.com/ljharb/qs/commit/f6a7abff1f13d644db9b05fe4f2c98ada6bf8482
	7ffcee3d-2c14-4c3e-b844-86c6a321a158	https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "### Summary\nThe `arrayLimit` option in qs does not enforce limits for comma-separated values when `comma: true` is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of the array limit enforcement, similar to the bracket notation bypass addressed in GHSA-6rw7-vpxm-498p (CVE-2025-15284).\n\n### Details\nWhen the `comma` option is set to `true` (not the default, but configurable in applications), qs allows parsing comma-separated strings as arrays (e.g., `?param=a,b,c` becomes `[\u0027a\u0027, \u0027b\u0027, \u0027c\u0027]`). However, the limit check for `arrayLimit` (default: 20) and the optional throwOnLimitExceeded occur after the comma-handling logic in `parseArrayValue`, enabling a bypass. This permits creation of arbitrarily large arrays from a single parameter, leading to excessive memory allocation.\n\n**Vulnerable code** (lib/parse.js: lines ~40-50):\n```js\nif (val \u0026\u0026 typeof val === \u0027string\u0027 \u0026\u0026 options.comma \u0026\u0026 val.indexOf(\u0027,\u0027) \u003e -1) {\n\u00a0 \u00a0 return val.split(\u0027,\u0027);\n}\n\nif (options.throwOnLimitExceeded \u0026\u0026 currentArrayLength \u003e= options.arrayLimit) {\n\u00a0 \u00a0 throw new RangeError(\u0027Array limit exceeded. Only \u0027 + options.arrayLimit + \u0027 element\u0027 + (options.arrayLimit === 1 ? \u0027\u0027 : \u0027s\u0027) + \u0027 allowed in an array.\u0027);\n}\n\nreturn val;\n```\nThe `split(\u0027,\u0027)` returns the array immediately, skipping the subsequent limit check. Downstream merging via `utils.combine` does not prevent allocation, even if it marks overflows for sparse arrays.This discrepancy allows attackers to send a single parameter with millions of commas (e.g., `?param=,,,,,,,,...`), allocating massive arrays in memory without triggering limits. It bypasses the intent of `arrayLimit`, which is enforced correctly for indexed (`a[0]=`) and bracket (`a[]=`) notations (the latter fixed in v6.14.1 per GHSA-6rw7-vpxm-498p).\n\n### PoC\n**Test 1 - Basic bypass:**\n```\nnpm install qs\n```\n\n```js\nconst qs = require(\u0027qs\u0027);\n\nconst payload = \u0027a=\u0027 + \u0027,\u0027.repeat(25);  // 26 elements after split (bypasses arrayLimit: 5)\nconst options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true };\n\ntry {\n\u00a0 const result = qs.parse(payload, options);\n\u00a0 console.log(result.a.length);  // Outputs: 26 (bypass successful)\n} catch (e) {\n\u00a0 console.log(\u0027Limit enforced:\u0027, e.message);  // Not thrown\n}\n```\n**Configuration:**\n- `comma: true`\n- `arrayLimit: 5`\n- `throwOnLimitExceeded: true`\n\nExpected: Throws \"Array limit exceeded\" error.\nActual: Parses successfully, creating an array of length 26.\n\n\n### Impact\nDenial of Service (DoS) via memory exhaustion."
    }
  ],
  "id": "CVE-2026-2391",
  "lastModified": "2026-02-12T16:16:19.440",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 3.7,
          "baseSeverity": "LOW",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 2.2,
        "impactScore": 1.4,
        "source": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
        "type": "Secondary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.3,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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",
          "version": "4.0",
          "vulnAvailabilityImpact": "LOW",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-02-12T05:17:11.187",
  "references": [
    {
      "source": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
      "url": "https://github.com/ljharb/qs/commit/f6a7abff1f13d644db9b05fe4f2c98ada6bf8482"
    },
    {
      "source": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
      "url": "https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883"
    }
  ],
  "sourceIdentifier": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
  "vulnStatus": "Undergoing Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-20"
        }
      ],
      "source": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
      "type": "Secondary"
    }
  ]
}

Sightings

Author	Source	Type	Date

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.

Action not permitted

CVE-2026-2391 (GCVE-0-2026-2391)

GHSA-W7FW-MJWX-W883

Summary

Details

PoC

Impact

Suggested Fix

FKIE_CVE-2026-2391

Tags

Sightings

Nomenclature