Vulnerability-Lookup

CVE-2026-8723 (GCVE-0-2026-8723)

Vulnerability from cvelistv5 – Published: 2026-05-16 23:21 – Updated: 2026-05-18 14:02

Title

qs.stringify crashes on null/undefined entries in comma-format arrays under encodeValuesOnly

Summary

### Summary `qs.stringify` throws `TypeError` when called with `arrayFormat: 'comma'` and `encodeValuesOnly: true` on an array containing `null` or `undefined`. The throw is synchronous and not handled by any of qs's null-related options (`skipNulls`, `strictNullHandling`). ### Details In the comma + `encodeValuesOnly` branch, `lib/stringify.js:145` mapped the array through the raw encoder before joining: ```js obj = utils.maybeMap(obj, encoder); ``` `utils.encode` (`lib/utils.js:195`) reads `str.length` with no null guard, so a `null` or `undefined` element throws `TypeError`. `skipNulls` and `strictNullHandling` are both checked in the per-element loop below this line and never get a chance to run. Same class of bug as the filter-array path fixed in 0c180a4. The vulnerable shape of the comma + `encodeValuesOnly` branch was introduced in 4c4b23d ("encode comma values more consistently", PR #463, 2023-01-19), first released in v6.11.1. #### PoC ```js const qs = require('qs'); qs.stringify({ a: [null, 'b'] }, { arrayFormat: 'comma', encodeValuesOnly: true }); qs.stringify({ a: [undefined, 'b'] }, { arrayFormat: 'comma', encodeValuesOnly: true }); qs.stringify({ a: [null] }, { arrayFormat: 'comma', encodeValuesOnly: true }); // TypeError: Cannot read properties of null (reading 'length') // at encode (lib/utils.js:195:13) // at Object.maybeMap (lib/utils.js:322:37) // at stringify (lib/stringify.js:145:25) ``` #### Fix `lib/stringify.js:145`, applied in 21f80b3 on `main` and released as v6.15.2: ```diff - obj = utils.maybeMap(obj, encoder); + obj = utils.maybeMap(obj, function (v) { + return v == null ? v : encoder(v); + }); ``` `null` and `undefined` now pass through `maybeMap` unchanged and reach the `join(',')` step as-is. For `{ a: [null, 'b'] }` this produces `a=,b`, matching the non-`encodeValuesOnly` comma path (which already joins before encoding and produces `a=%2Cb` for the same input). Single-element `[null]` arrays still collapse via the existing `obj.join(',') || null` and remain subject to `skipNulls` / `strictNullHandling` in the main loop. ### Affected versions `>=6.11.1 <6.15.2` — fixed in v6.15.2. The vulnerable code shape was introduced in 4c4b23d and first shipped in v6.11.1. Earlier versions — including all of 6.7.x, 6.8.x, 6.9.x, 6.10.x, and 6.11.0 — implemented the comma + `encodeValuesOnly` path differently (joining before encoding) and are not affected. Empirically verified across released versions. ### Impact Application code that calls `qs.stringify` with both `arrayFormat: 'comma'` and `encodeValuesOnly: true` (both non-default) on input that may contain a `null` or `undefined` array element will throw synchronously instead of producing a query string. In a typical Node.js HTTP framework (Express, Fastify, Koa, hapi) the sync throw is caught by the framework's error boundary and the affected request returns a 500; the worker process does not exit and subsequent requests are unaffected. The "kills the worker process" framing applies only to call sites outside a request-handler error boundary (background jobs, startup paths, stream pipelines) or to deployments with framework error handling explicitly disabled. The vulnerable input is a `null` or `undefined` entry inside an array; this is reachable from JSON request bodies or from application code constructing arrays from user input, but not from standard HTML form submissions (which produce strings or omitted fields, not literal `null`).

Severity

5.3 (Medium)


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

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

CWE

CWE-476 - NULL Pointer Dereference

Assigner

harborist

References

2 references

URL	Tags
https://github.com/ljharb/qs/security/advisories/…	vendor-advisory
https://github.com/ljharb/qs/commit/21f80b33e5c8b…	patch

Impacted products

1 product

Vendor	Product	Version
ljharb	qs	Affected: 6.11.1 , < 6.15.2 (semver)

Credits

joannalange

Show details on NVD website

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              "value": "\u003cp\u003e### Summary\u003c/p\u003e\u003cp\u003e`qs.stringify` throws `TypeError` when called with `arrayFormat: \u0027comma\u0027` and `encodeValuesOnly: true` on an array containing `null` or `undefined`. The throw is synchronous and not handled by any of qs\u0027s null-related options (`skipNulls`, `strictNullHandling`).\u003c/p\u003e\u003cp\u003e### Details\u003c/p\u003e\u003cp\u003eIn the comma + `encodeValuesOnly` branch, `lib/stringify.js:145` mapped the array through the raw encoder before joining:\u003c/p\u003e\u003cp\u003e```js\u003c/p\u003e\u003cp\u003eobj = utils.maybeMap(obj, encoder);\u003c/p\u003e\u003cp\u003e```\u003c/p\u003e\u003cp\u003e`utils.encode` (`lib/utils.js:195`) reads `str.length` with no null guard, so a `null` or `undefined` element throws `TypeError`. `skipNulls` and `strictNullHandling` are both checked in the per-element loop below this line and never get a chance to run.\u003c/p\u003e\u003cp\u003eSame class of bug as the filter-array path fixed in 0c180a4. The vulnerable shape of the comma + `encodeValuesOnly` branch was introduced in 4c4b23d (\"encode comma values more consistently\", PR #463, 2023-01-19), first released in v6.11.1.\u003c/p\u003e\u003cp\u003e#### PoC\u003c/p\u003e\u003cp\u003e```js\u003c/p\u003e\u003cp\u003econst qs = require(\u0027qs\u0027);\u003c/p\u003e\u003cp\u003eqs.stringify({ a: [null, \u0027b\u0027] },      { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\u003c/p\u003e\u003cp\u003eqs.stringify({ a: [undefined, \u0027b\u0027] }, { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\u003c/p\u003e\u003cp\u003eqs.stringify({ a: [null] },           { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\u003c/p\u003e\u003cp\u003e// TypeError: Cannot read properties of null (reading \u0027length\u0027)\u003c/p\u003e\u003cp\u003e//     at encode (lib/utils.js:195:13)\u003c/p\u003e\u003cp\u003e//     at Object.maybeMap (lib/utils.js:322:37)\u003c/p\u003e\u003cp\u003e//     at stringify (lib/stringify.js:145:25)\u003c/p\u003e\u003cp\u003e```\u003c/p\u003e\u003cp\u003e#### Fix\u003c/p\u003e\u003cp\u003e`lib/stringify.js:145`, applied in 21f80b3 on `main` and released as v6.15.2:\u003c/p\u003e\u003cp\u003e```diff\u003c/p\u003e\u003cp\u003e- obj = utils.maybeMap(obj, encoder);\u003c/p\u003e\u003cp\u003e+ obj = utils.maybeMap(obj, function (v) {\u003c/p\u003e\u003cp\u003e+     return v == null ? v : encoder(v);\u003c/p\u003e\u003cp\u003e+ });\u003c/p\u003e\u003cp\u003e```\u003c/p\u003e\u003cp\u003e`null` and `undefined` now pass through `maybeMap` unchanged and reach the `join(\u0027,\u0027)` step as-is. For `{ a: [null, \u0027b\u0027] }` this produces `a=,b`, matching the non-`encodeValuesOnly` comma path (which already joins before encoding and produces `a=%2Cb` for the same input). Single-element `[null]` arrays still collapse via the existing `obj.join(\u0027,\u0027) || null` and remain subject to `skipNulls` / `strictNullHandling` in the main loop.\u003c/p\u003e\u003cp\u003e### Affected versions\u003c/p\u003e\u003cp\u003e`\u0026gt;=6.11.1 \u0026lt;6.15.2` \u2014 fixed in v6.15.2.\u003c/p\u003e\u003cp\u003eThe vulnerable code shape was introduced in 4c4b23d and first shipped in v6.11.1. Earlier versions \u2014 including all of 6.7.x, 6.8.x, 6.9.x, 6.10.x, and 6.11.0 \u2014 implemented the comma + `encodeValuesOnly` path differently (joining before encoding) and are not affected. Empirically verified across released versions.\u003c/p\u003e\u003cp\u003e### Impact\u003c/p\u003e\u003cp\u003eApplication code that calls `qs.stringify` with both `arrayFormat: \u0027comma\u0027` and `encodeValuesOnly: true` (both non-default) on input that may contain a `null` or `undefined` array element will throw synchronously instead of producing a query string. In a typical Node.js HTTP framework (Express, Fastify, Koa, hapi) the sync throw is caught by the framework\u0027s error boundary and the affected request returns a 500; the worker process does not exit and subsequent requests are unaffected. The \"kills the worker process\" framing applies only to call sites outside a request-handler error boundary (background jobs, startup paths, stream pipelines) or to deployments with framework error handling explicitly disabled.\u003c/p\u003e\u003cp\u003eThe vulnerable input is a `null` or `undefined` entry inside an array; this is reachable from JSON request bodies or from application code constructing arrays from user input, but not from standard HTML form submissions (which produce strings or omitted fields, not literal `null`).\u003c/p\u003e"
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      "title": "qs.stringify crashes on null/undefined entries in comma-format arrays under encodeValuesOnly"
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The throw is synchronous and not handled by any of qs\u0027s null-related options (`skipNulls`, `strictNullHandling`).\\n\\n\\n\\n### Details\\n\\n\\n\\nIn the comma + `encodeValuesOnly` branch, `lib/stringify.js:145` mapped the array through the raw encoder before joining:\\n\\n\\n\\n```js\\n\\n\\n\\nobj = utils.maybeMap(obj, encoder);\\n\\n\\n\\n```\\n\\n\\n\\n`utils.encode` (`lib/utils.js:195`) reads `str.length` with no null guard, so a `null` or `undefined` element throws `TypeError`. `skipNulls` and `strictNullHandling` are both checked in the per-element loop below this line and never get a chance to run.\\n\\n\\n\\nSame class of bug as the filter-array path fixed in 0c180a4. The vulnerable shape of the comma + `encodeValuesOnly` branch was introduced in 4c4b23d (\\\"encode comma values more consistently\\\", PR #463, 2023-01-19), first released in v6.11.1.\\n\\n\\n\\n#### PoC\\n\\n\\n\\n```js\\n\\n\\n\\nconst qs = require(\u0027qs\u0027);\\n\\n\\n\\nqs.stringify({ a: [null, \u0027b\u0027] },      { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\\n\\n\\n\\nqs.stringify({ a: [undefined, \u0027b\u0027] }, { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\\n\\n\\n\\nqs.stringify({ a: [null] },           { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\\n\\n\\n\\n// TypeError: Cannot read properties of null (reading \u0027length\u0027)\\n\\n\\n\\n//     at encode (lib/utils.js:195:13)\\n\\n\\n\\n//     at Object.maybeMap (lib/utils.js:322:37)\\n\\n\\n\\n//     at stringify (lib/stringify.js:145:25)\\n\\n\\n\\n```\\n\\n\\n\\n#### Fix\\n\\n\\n\\n`lib/stringify.js:145`, applied in 21f80b3 on `main` and released as v6.15.2:\\n\\n\\n\\n```diff\\n\\n\\n\\n- obj = utils.maybeMap(obj, encoder);\\n\\n\\n\\n+ obj = utils.maybeMap(obj, function (v) {\\n\\n\\n\\n+     return v == null ? v : encoder(v);\\n\\n\\n\\n+ });\\n\\n\\n\\n```\\n\\n\\n\\n`null` and `undefined` now pass through `maybeMap` unchanged and reach the `join(\u0027,\u0027)` step as-is. For `{ a: [null, \u0027b\u0027] }` this produces `a=,b`, matching the non-`encodeValuesOnly` comma path (which already joins before encoding and produces `a=%2Cb` for the same input). Single-element `[null]` arrays still collapse via the existing `obj.join(\u0027,\u0027) || null` and remain subject to `skipNulls` / `strictNullHandling` in the main loop.\\n\\n\\n\\n### Affected versions\\n\\n\\n\\n`\u003e=6.11.1 \u003c6.15.2` \u2014 fixed in v6.15.2.\\n\\n\\n\\nThe vulnerable code shape was introduced in 4c4b23d and first shipped in v6.11.1. Earlier versions \u2014 including all of 6.7.x, 6.8.x, 6.9.x, 6.10.x, and 6.11.0 \u2014 implemented the comma + `encodeValuesOnly` path differently (joining before encoding) and are not affected. Empirically verified across released versions.\\n\\n\\n\\n### Impact\\n\\n\\n\\nApplication code that calls `qs.stringify` with both `arrayFormat: \u0027comma\u0027` and `encodeValuesOnly: true` (both non-default) on input that may contain a `null` or `undefined` array element will throw synchronously instead of producing a query string. In a typical Node.js HTTP framework (Express, Fastify, Koa, hapi) the sync throw is caught by the framework\u0027s error boundary and the affected request returns a 500; the worker process does not exit and subsequent requests are unaffected. The \\\"kills the worker process\\\" framing applies only to call sites outside a request-handler error boundary (background jobs, startup paths, stream pipelines) or to deployments with framework error handling explicitly disabled.\\n\\n\\n\\nThe vulnerable input is a `null` or `undefined` entry inside an array; this is reachable from JSON request bodies or from application code constructing arrays from user input, but not from standard HTML form submissions (which produce strings or omitted fields, not literal `null`).\"}],\"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:L/PR:N/UI:N/S:U/C:N/I:N/A:L\",\"baseScore\":5.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"LOW\"},\"exploitabilityScore\":3.9,\"impactScore\":1.4}]},\"weaknesses\":[{\"source\":\"7ffcee3d-2c14-4c3e-b844-86c6a321a158\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-476\"}]}],\"references\":[{\"url\":\"https://github.com/ljharb/qs/commit/21f80b33e5c8b3f7eba1034fff0da4a4a37a1d41\",\"source\":\"7ffcee3d-2c14-4c3e-b844-86c6a321a158\"},{\"url\":\"https://github.com/ljharb/qs/security/advisories/GHSA-q8mj-m7cp-5q26\",\"source\":\"7ffcee3d-2c14-4c3e-b844-86c6a321a158\"},{\"url\":\"https://github.com/ljharb/qs/security/advisories/GHSA-q8mj-m7cp-5q26\",\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\"}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-8723\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-05-18T14:02:12.499337Z\"}}}], \"references\": [{\"url\": \"https://github.com/ljharb/qs/security/advisories/GHSA-q8mj-m7cp-5q26\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-05-18T14:02:54.077Z\"}}], \"cna\": {\"title\": \"qs.stringify crashes on null/undefined entries in comma-format arrays under encodeValuesOnly\", \"source\": {\"discovery\": \"EXTERNAL\"}, \"credits\": [{\"lang\": \"en\", \"type\": \"reporter\", \"value\": \"joannalange\"}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 5.3, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"LOW\", \"privilegesRequired\": \"NONE\", \"confidentialityImpact\": \"NONE\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}, {\"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\"}]}], \"affected\": [{\"repo\": \"https://github.com/ljharb/qs\", \"vendor\": \"ljharb\", \"product\": \"qs\", \"versions\": [{\"status\": \"affected\", \"version\": \"6.11.1\", \"lessThan\": \"6.15.2\", \"versionType\": \"semver\"}], \"packageName\": \"qs\", \"collectionURL\": \"https://npmjs.com/qs\", \"defaultStatus\": \"unaffected\"}], \"references\": [{\"url\": \"https://github.com/ljharb/qs/security/advisories/GHSA-q8mj-m7cp-5q26\", \"tags\": [\"vendor-advisory\"]}, {\"url\": \"https://github.com/ljharb/qs/commit/21f80b33e5c8b3f7eba1034fff0da4a4a37a1d41\", \"tags\": [\"patch\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"### Summary\\n\\n\\n\\n`qs.stringify` throws `TypeError` when called with `arrayFormat: \u0027comma\u0027` and `encodeValuesOnly: true` on an array containing `null` or `undefined`. The throw is synchronous and not handled by any of qs\u0027s null-related options (`skipNulls`, `strictNullHandling`).\\n\\n\\n\\n### Details\\n\\n\\n\\nIn the comma + `encodeValuesOnly` branch, `lib/stringify.js:145` mapped the array through the raw encoder before joining:\\n\\n\\n\\n```js\\n\\n\\n\\nobj = utils.maybeMap(obj, encoder);\\n\\n\\n\\n```\\n\\n\\n\\n`utils.encode` (`lib/utils.js:195`) reads `str.length` with no null guard, so a `null` or `undefined` element throws `TypeError`. `skipNulls` and `strictNullHandling` are both checked in the per-element loop below this line and never get a chance to run.\\n\\n\\n\\nSame class of bug as the filter-array path fixed in 0c180a4. The vulnerable shape of the comma + `encodeValuesOnly` branch was introduced in 4c4b23d (\\\"encode comma values more consistently\\\", PR #463, 2023-01-19), first released in v6.11.1.\\n\\n\\n\\n#### PoC\\n\\n\\n\\n```js\\n\\n\\n\\nconst qs = require(\u0027qs\u0027);\\n\\n\\n\\nqs.stringify({ a: [null, \u0027b\u0027] },      { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\\n\\n\\n\\nqs.stringify({ a: [undefined, \u0027b\u0027] }, { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\\n\\n\\n\\nqs.stringify({ a: [null] },           { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\\n\\n\\n\\n// TypeError: Cannot read properties of null (reading \u0027length\u0027)\\n\\n\\n\\n//     at encode (lib/utils.js:195:13)\\n\\n\\n\\n//     at Object.maybeMap (lib/utils.js:322:37)\\n\\n\\n\\n//     at stringify (lib/stringify.js:145:25)\\n\\n\\n\\n```\\n\\n\\n\\n#### Fix\\n\\n\\n\\n`lib/stringify.js:145`, applied in 21f80b3 on `main` and released as v6.15.2:\\n\\n\\n\\n```diff\\n\\n\\n\\n- obj = utils.maybeMap(obj, encoder);\\n\\n\\n\\n+ obj = utils.maybeMap(obj, function (v) {\\n\\n\\n\\n+     return v == null ? v : encoder(v);\\n\\n\\n\\n+ });\\n\\n\\n\\n```\\n\\n\\n\\n`null` and `undefined` now pass through `maybeMap` unchanged and reach the `join(\u0027,\u0027)` step as-is. For `{ a: [null, \u0027b\u0027] }` this produces `a=,b`, matching the non-`encodeValuesOnly` comma path (which already joins before encoding and produces `a=%2Cb` for the same input). Single-element `[null]` arrays still collapse via the existing `obj.join(\u0027,\u0027) || null` and remain subject to `skipNulls` / `strictNullHandling` in the main loop.\\n\\n\\n\\n### Affected versions\\n\\n\\n\\n`\u003e=6.11.1 \u003c6.15.2` \\u2014 fixed in v6.15.2.\\n\\n\\n\\nThe vulnerable code shape was introduced in 4c4b23d and first shipped in v6.11.1. Earlier versions \\u2014 including all of 6.7.x, 6.8.x, 6.9.x, 6.10.x, and 6.11.0 \\u2014 implemented the comma + `encodeValuesOnly` path differently (joining before encoding) and are not affected. Empirically verified across released versions.\\n\\n\\n\\n### Impact\\n\\n\\n\\nApplication code that calls `qs.stringify` with both `arrayFormat: \u0027comma\u0027` and `encodeValuesOnly: true` (both non-default) on input that may contain a `null` or `undefined` array element will throw synchronously instead of producing a query string. In a typical Node.js HTTP framework (Express, Fastify, Koa, hapi) the sync throw is caught by the framework\u0027s error boundary and the affected request returns a 500; the worker process does not exit and subsequent requests are unaffected. The \\\"kills the worker process\\\" framing applies only to call sites outside a request-handler error boundary (background jobs, startup paths, stream pipelines) or to deployments with framework error handling explicitly disabled.\\n\\n\\n\\nThe vulnerable input is a `null` or `undefined` entry inside an array; this is reachable from JSON request bodies or from application code constructing arrays from user input, but not from standard HTML form submissions (which produce strings or omitted fields, not literal `null`).\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003e### Summary\u003c/p\u003e\u003cp\u003e`qs.stringify` throws `TypeError` when called with `arrayFormat: \u0027comma\u0027` and `encodeValuesOnly: true` on an array containing `null` or `undefined`. The throw is synchronous and not handled by any of qs\u0027s null-related options (`skipNulls`, `strictNullHandling`).\u003c/p\u003e\u003cp\u003e### Details\u003c/p\u003e\u003cp\u003eIn the comma + `encodeValuesOnly` branch, `lib/stringify.js:145` mapped the array through the raw encoder before joining:\u003c/p\u003e\u003cp\u003e```js\u003c/p\u003e\u003cp\u003eobj = utils.maybeMap(obj, encoder);\u003c/p\u003e\u003cp\u003e```\u003c/p\u003e\u003cp\u003e`utils.encode` (`lib/utils.js:195`) reads `str.length` with no null guard, so a `null` or `undefined` element throws `TypeError`. `skipNulls` and `strictNullHandling` are both checked in the per-element loop below this line and never get a chance to run.\u003c/p\u003e\u003cp\u003eSame class of bug as the filter-array path fixed in 0c180a4. The vulnerable shape of the comma + `encodeValuesOnly` branch was introduced in 4c4b23d (\\\"encode comma values more consistently\\\", PR #463, 2023-01-19), first released in v6.11.1.\u003c/p\u003e\u003cp\u003e#### PoC\u003c/p\u003e\u003cp\u003e```js\u003c/p\u003e\u003cp\u003econst qs = require(\u0027qs\u0027);\u003c/p\u003e\u003cp\u003eqs.stringify({ a: [null, \u0027b\u0027] },      { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\u003c/p\u003e\u003cp\u003eqs.stringify({ a: [undefined, \u0027b\u0027] }, { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\u003c/p\u003e\u003cp\u003eqs.stringify({ a: [null] },           { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\u003c/p\u003e\u003cp\u003e// TypeError: Cannot read properties of null (reading \u0027length\u0027)\u003c/p\u003e\u003cp\u003e//     at encode (lib/utils.js:195:13)\u003c/p\u003e\u003cp\u003e//     at Object.maybeMap (lib/utils.js:322:37)\u003c/p\u003e\u003cp\u003e//     at stringify (lib/stringify.js:145:25)\u003c/p\u003e\u003cp\u003e```\u003c/p\u003e\u003cp\u003e#### Fix\u003c/p\u003e\u003cp\u003e`lib/stringify.js:145`, applied in 21f80b3 on `main` and released as v6.15.2:\u003c/p\u003e\u003cp\u003e```diff\u003c/p\u003e\u003cp\u003e- obj = utils.maybeMap(obj, encoder);\u003c/p\u003e\u003cp\u003e+ obj = utils.maybeMap(obj, function (v) {\u003c/p\u003e\u003cp\u003e+     return v == null ? v : encoder(v);\u003c/p\u003e\u003cp\u003e+ });\u003c/p\u003e\u003cp\u003e```\u003c/p\u003e\u003cp\u003e`null` and `undefined` now pass through `maybeMap` unchanged and reach the `join(\u0027,\u0027)` step as-is. For `{ a: [null, \u0027b\u0027] }` this produces `a=,b`, matching the non-`encodeValuesOnly` comma path (which already joins before encoding and produces `a=%2Cb` for the same input). Single-element `[null]` arrays still collapse via the existing `obj.join(\u0027,\u0027) || null` and remain subject to `skipNulls` / `strictNullHandling` in the main loop.\u003c/p\u003e\u003cp\u003e### Affected versions\u003c/p\u003e\u003cp\u003e`\u0026gt;=6.11.1 \u0026lt;6.15.2` \\u2014 fixed in v6.15.2.\u003c/p\u003e\u003cp\u003eThe vulnerable code shape was introduced in 4c4b23d and first shipped in v6.11.1. Earlier versions \\u2014 including all of 6.7.x, 6.8.x, 6.9.x, 6.10.x, and 6.11.0 \\u2014 implemented the comma + `encodeValuesOnly` path differently (joining before encoding) and are not affected. Empirically verified across released versions.\u003c/p\u003e\u003cp\u003e### Impact\u003c/p\u003e\u003cp\u003eApplication code that calls `qs.stringify` with both `arrayFormat: \u0027comma\u0027` and `encodeValuesOnly: true` (both non-default) on input that may contain a `null` or `undefined` array element will throw synchronously instead of producing a query string. In a typical Node.js HTTP framework (Express, Fastify, Koa, hapi) the sync throw is caught by the framework\u0027s error boundary and the affected request returns a 500; the worker process does not exit and subsequent requests are unaffected. The \\\"kills the worker process\\\" framing applies only to call sites outside a request-handler error boundary (background jobs, startup paths, stream pipelines) or to deployments with framework error handling explicitly disabled.\u003c/p\u003e\u003cp\u003eThe vulnerable input is a `null` or `undefined` entry inside an array; this is reachable from JSON request bodies or from application code constructing arrays from user input, but not from standard HTML form submissions (which produce strings or omitted fields, not literal `null`).\u003c/p\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-476\", \"description\": \"CWE-476 NULL Pointer Dereference\"}]}], \"providerMetadata\": {\"orgId\": \"7ffcee3d-2c14-4c3e-b844-86c6a321a158\", \"shortName\": \"harborist\", \"dateUpdated\": \"2026-05-16T23:21:16.035Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-8723\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-05-18T14:02:57.825Z\", \"dateReserved\": \"2026-05-16T06:26:43.607Z\", \"assignerOrgId\": \"7ffcee3d-2c14-4c3e-b844-86c6a321a158\", \"datePublished\": \"2026-05-16T23:21:16.035Z\", \"assignerShortName\": \"harborist\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
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}

FKIE_CVE-2026-8723

Vulnerability from fkie_nvd - Published: 2026-05-17 00:16 - Updated: 2026-05-18 20:23

Severity

5.3 (Medium) - CVSS:3.1/AV:N/AC:L/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/21f80b33e5c8b3f7eba1034fff0da4a4a37a1d41
	7ffcee3d-2c14-4c3e-b844-86c6a321a158	https://github.com/ljharb/qs/security/advisories/GHSA-q8mj-m7cp-5q26
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/ljharb/qs/security/advisories/GHSA-q8mj-m7cp-5q26

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "### Summary\n\n\n\n`qs.stringify` throws `TypeError` when called with `arrayFormat: \u0027comma\u0027` and `encodeValuesOnly: true` on an array containing `null` or `undefined`. The throw is synchronous and not handled by any of qs\u0027s null-related options (`skipNulls`, `strictNullHandling`).\n\n\n\n### Details\n\n\n\nIn the comma + `encodeValuesOnly` branch, `lib/stringify.js:145` mapped the array through the raw encoder before joining:\n\n\n\n```js\n\n\n\nobj = utils.maybeMap(obj, encoder);\n\n\n\n```\n\n\n\n`utils.encode` (`lib/utils.js:195`) reads `str.length` with no null guard, so a `null` or `undefined` element throws `TypeError`. `skipNulls` and `strictNullHandling` are both checked in the per-element loop below this line and never get a chance to run.\n\n\n\nSame class of bug as the filter-array path fixed in 0c180a4. The vulnerable shape of the comma + `encodeValuesOnly` branch was introduced in 4c4b23d (\"encode comma values more consistently\", PR #463, 2023-01-19), first released in v6.11.1.\n\n\n\n#### PoC\n\n\n\n```js\n\n\n\nconst qs = require(\u0027qs\u0027);\n\n\n\nqs.stringify({ a: [null, \u0027b\u0027] },      { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\n\n\n\nqs.stringify({ a: [undefined, \u0027b\u0027] }, { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\n\n\n\nqs.stringify({ a: [null] },           { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\n\n\n\n// TypeError: Cannot read properties of null (reading \u0027length\u0027)\n\n\n\n//     at encode (lib/utils.js:195:13)\n\n\n\n//     at Object.maybeMap (lib/utils.js:322:37)\n\n\n\n//     at stringify (lib/stringify.js:145:25)\n\n\n\n```\n\n\n\n#### Fix\n\n\n\n`lib/stringify.js:145`, applied in 21f80b3 on `main` and released as v6.15.2:\n\n\n\n```diff\n\n\n\n- obj = utils.maybeMap(obj, encoder);\n\n\n\n+ obj = utils.maybeMap(obj, function (v) {\n\n\n\n+     return v == null ? v : encoder(v);\n\n\n\n+ });\n\n\n\n```\n\n\n\n`null` and `undefined` now pass through `maybeMap` unchanged and reach the `join(\u0027,\u0027)` step as-is. For `{ a: [null, \u0027b\u0027] }` this produces `a=,b`, matching the non-`encodeValuesOnly` comma path (which already joins before encoding and produces `a=%2Cb` for the same input). Single-element `[null]` arrays still collapse via the existing `obj.join(\u0027,\u0027) || null` and remain subject to `skipNulls` / `strictNullHandling` in the main loop.\n\n\n\n### Affected versions\n\n\n\n`\u003e=6.11.1 \u003c6.15.2` \u2014 fixed in v6.15.2.\n\n\n\nThe vulnerable code shape was introduced in 4c4b23d and first shipped in v6.11.1. Earlier versions \u2014 including all of 6.7.x, 6.8.x, 6.9.x, 6.10.x, and 6.11.0 \u2014 implemented the comma + `encodeValuesOnly` path differently (joining before encoding) and are not affected. Empirically verified across released versions.\n\n\n\n### Impact\n\n\n\nApplication code that calls `qs.stringify` with both `arrayFormat: \u0027comma\u0027` and `encodeValuesOnly: true` (both non-default) on input that may contain a `null` or `undefined` array element will throw synchronously instead of producing a query string. In a typical Node.js HTTP framework (Express, Fastify, Koa, hapi) the sync throw is caught by the framework\u0027s error boundary and the affected request returns a 500; the worker process does not exit and subsequent requests are unaffected. The \"kills the worker process\" framing applies only to call sites outside a request-handler error boundary (background jobs, startup paths, stream pipelines) or to deployments with framework error handling explicitly disabled.\n\n\n\nThe vulnerable input is a `null` or `undefined` entry inside an array; this is reachable from JSON request bodies or from application code constructing arrays from user input, but not from standard HTML form submissions (which produce strings or omitted fields, not literal `null`)."
    }
  ],
  "id": "CVE-2026-8723",
  "lastModified": "2026-05-18T20:23:20.240",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "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": "2026-05-17T00:16:21.233",
  "references": [
    {
      "source": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
      "url": "https://github.com/ljharb/qs/commit/21f80b33e5c8b3f7eba1034fff0da4a4a37a1d41"
    },
    {
      "source": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
      "url": "https://github.com/ljharb/qs/security/advisories/GHSA-q8mj-m7cp-5q26"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/ljharb/qs/security/advisories/GHSA-q8mj-m7cp-5q26"
    }
  ],
  "sourceIdentifier": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ],
      "source": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
      "type": "Secondary"
    }
  ]
}

GHSA-Q8MJ-M7CP-5Q26

Vulnerability from github – Published: 2026-05-22 17:27 – Updated: 2026-05-22 17:27

Summary

qs has a remotely triggerable DoS: qs.stringify crashes with TypeError on null/undefined entries in comma-format arrays when encodeValuesOnly is set

Details

Summary

qs.stringify throws TypeError when called with arrayFormat: 'comma' and encodeValuesOnly: true on an array containing null or undefined. The throw is synchronous and not handled by any of qs's null-related options (skipNulls, strictNullHandling).

Details

In the comma + encodeValuesOnly branch, lib/stringify.js:145 mapped the array through the raw encoder before joining:

obj = utils.maybeMap(obj, encoder);

utils.encode (lib/utils.js:195) reads str.length with no null guard, so a null or undefined element throws TypeError. skipNulls and strictNullHandling are both checked in the per-element loop below this line and never get a chance to run.

Same class of bug as the filter-array path fixed in 0c180a4. The vulnerable shape of the comma + encodeValuesOnly branch was introduced in 4c4b23d ("encode comma values more consistently", PR #463, 2023-01-19), first released in v6.11.1.

PoC

const qs = require('qs');

qs.stringify({ a: [null, 'b'] },      { arrayFormat: 'comma', encodeValuesOnly: true });
qs.stringify({ a: [undefined, 'b'] }, { arrayFormat: 'comma', encodeValuesOnly: true });
qs.stringify({ a: [null] },           { arrayFormat: 'comma', encodeValuesOnly: true });
// TypeError: Cannot read properties of null (reading 'length')
//     at encode (lib/utils.js:195:13)
//     at Object.maybeMap (lib/utils.js:322:37)
//     at stringify (lib/stringify.js:145:25)

Fix

lib/stringify.js:145, applied in 21f80b3 on main:

- obj = utils.maybeMap(obj, encoder);
+ obj = utils.maybeMap(obj, function (v) {
+     return v == null ? v : encoder(v);
+ });

null and undefined now pass through maybeMap unchanged and reach the join(',') step as-is. For { a: [null, 'b'] } this produces a=,b, matching the non-encodeValuesOnly comma path (which already joins before encoding and produces a=%2Cb for the same input). Single-element [null] arrays still collapse via the existing obj.join(',') || null and remain subject to skipNulls / strictNullHandling in the main loop.

Affected versions

>=6.11.1 <=6.15.1

The vulnerable code shape was introduced in 4c4b23d and first shipped in v6.11.1. Earlier versions — including all of 6.7.x, 6.8.x, 6.9.x, 6.10.x, and 6.11.0 — implemented the comma + encodeValuesOnly path differently (joining before encoding) and are not affected. Empirically verified across released versions.

Impact

Application code that calls qs.stringify with both arrayFormat: 'comma' and encodeValuesOnly: true (both non-default) on input that may contain a null or undefined array element will throw synchronously instead of producing a query string. In a typical Node.js HTTP framework (Express, Fastify, Koa, hapi) the sync throw is caught by the framework's error boundary and the affected request returns a 500; the worker process does not exit and subsequent requests are unaffected. The "kills the worker process" framing applies only to call sites outside a request-handler error boundary (background jobs, startup paths, stream pipelines) or to deployments with framework error handling explicitly disabled.

The vulnerable input is a null or undefined entry inside an array; this is reachable from JSON request bodies or from application code constructing arrays from user input, but not from standard HTML form submissions (which produce strings or omitted fields, not literal null).

Severity

5.3 (Medium)


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

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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 6.15.1"
      },
      "package": {
        "ecosystem": "npm",
        "name": "qs"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.11.1"
            },
            {
              "fixed": "6.15.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-8723"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-22T17:27:19Z",
    "nvd_published_at": "2026-05-17T00:16:21Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\n`qs.stringify` throws `TypeError` when called with `arrayFormat: \u0027comma\u0027` and `encodeValuesOnly: true` on an array containing `null` or `undefined`. The throw is synchronous and not handled by any of qs\u0027s null-related options (`skipNulls`, `strictNullHandling`).\n\n### Details\n\nIn the comma + `encodeValuesOnly` branch, `lib/stringify.js:145` mapped the array through the raw encoder before joining:\n\n```js\nobj = utils.maybeMap(obj, encoder);\n```\n\n`utils.encode` (`lib/utils.js:195`) reads `str.length` with no null guard, so a `null` or `undefined` element throws `TypeError`. `skipNulls` and `strictNullHandling` are both checked in the per-element loop below this line and never get a chance to run.\n\nSame class of bug as the filter-array path fixed in 0c180a4. The vulnerable shape of the comma + `encodeValuesOnly` branch was introduced in 4c4b23d (\"encode comma values more consistently\", PR #463, 2023-01-19), first released in v6.11.1.\n\n#### PoC\n\n```js\nconst qs = require(\u0027qs\u0027);\n\nqs.stringify({ a: [null, \u0027b\u0027] },      { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\nqs.stringify({ a: [undefined, \u0027b\u0027] }, { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\nqs.stringify({ a: [null] },           { arrayFormat: \u0027comma\u0027, encodeValuesOnly: true });\n// TypeError: Cannot read properties of null (reading \u0027length\u0027)\n//     at encode (lib/utils.js:195:13)\n//     at Object.maybeMap (lib/utils.js:322:37)\n//     at stringify (lib/stringify.js:145:25)\n```\n\n#### Fix\n\n`lib/stringify.js:145`, applied in 21f80b3 on `main`:\n\n```diff\n- obj = utils.maybeMap(obj, encoder);\n+ obj = utils.maybeMap(obj, function (v) {\n+     return v == null ? v : encoder(v);\n+ });\n```\n\n`null` and `undefined` now pass through `maybeMap` unchanged and reach the `join(\u0027,\u0027)` step as-is. For `{ a: [null, \u0027b\u0027] }` this produces `a=,b`, matching the non-`encodeValuesOnly` comma path (which already joins before encoding and produces `a=%2Cb` for the same input). Single-element `[null]` arrays still collapse via the existing `obj.join(\u0027,\u0027) || null` and remain subject to `skipNulls` / `strictNullHandling` in the main loop.\n\n### Affected versions\n\n`\u003e=6.11.1 \u003c=6.15.1`\n\nThe vulnerable code shape was introduced in 4c4b23d and first shipped in v6.11.1. Earlier versions \u2014 including all of 6.7.x, 6.8.x, 6.9.x, 6.10.x, and 6.11.0 \u2014 implemented the comma + `encodeValuesOnly` path differently (joining before encoding) and are not affected. Empirically verified across released versions.\n\n### Impact\n\nApplication code that calls `qs.stringify` with both `arrayFormat: \u0027comma\u0027` and `encodeValuesOnly: true` (both non-default) on input that may contain a `null` or `undefined` array element will throw synchronously instead of producing a query string. In a typical Node.js HTTP framework (Express, Fastify, Koa, hapi) the sync throw is caught by the framework\u0027s error boundary and the affected request returns a 500; the worker process does not exit and subsequent requests are unaffected. The \"kills the worker process\" framing applies only to call sites outside a request-handler error boundary (background jobs, startup paths, stream pipelines) or to deployments with framework error handling explicitly disabled.\n\nThe vulnerable input is a `null` or `undefined` entry inside an array; this is reachable from JSON request bodies or from application code constructing arrays from user input, but not from standard HTML form submissions (which produce strings or omitted fields, not literal `null`).",
  "id": "GHSA-q8mj-m7cp-5q26",
  "modified": "2026-05-22T17:27:19Z",
  "published": "2026-05-22T17:27:19Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ljharb/qs/security/advisories/GHSA-q8mj-m7cp-5q26"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-8723"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ljharb/qs/commit/21f80b33e5c8b3f7eba1034fff0da4a4a37a1d41"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ljharb/qs"
    }
  ],
  "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"
    },
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "qs has a remotely triggerable DoS: qs.stringify crashes with TypeError on null/undefined entries in comma-format arrays when encodeValuesOnly is set"
}

MSRC_CVE-2026-8723

Vulnerability from csaf_microsoft - Published: 2026-05-02 00:00 - Updated: 2026-05-23 01:02

Summary

qs.stringify crashes on null/undefined entries in comma-format arrays under encodeValuesOnly

Notes

Additional Resources: To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle

Disclaimer: The information provided in the Microsoft Knowledge Base is provided \"as is\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.

CVE-2026-8723

5.3 (Medium)


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

CWE-476 - NULL Pointer Dereference

Affected products

Known affected 1 product

Product	Identifier	Version	Remediation
Unresolved product id: 17084-1		—	None Available

References

4 references

URL	Category
https://msrc.microsoft.com/csaf/vex/2026/msrc_cve…	self
https://support.microsoft.com/lifecycle	external
https://www.first.org/cvss	external
https://msrc.microsoft.com/csaf/vex/2026/msrc_cve…	self

JSON

To clipboard

{
  "document": {
    "category": "csaf_vex",
    "csaf_version": "2.0",
    "distribution": {
      "text": "Public",
      "tlp": {
        "label": "WHITE",
        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "en-US",
    "notes": [
      {
        "category": "general",
        "text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
        "title": "Additional Resources"
      },
      {
        "category": "legal_disclaimer",
        "text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
        "title": "Disclaimer"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "secure@microsoft.com",
      "name": "Microsoft Security Response Center",
      "namespace": "https://msrc.microsoft.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "CVE-2026-8723 qs.stringify crashes on null/undefined entries in comma-format arrays under encodeValuesOnly - VEX",
        "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-8723.json"
      },
      {
        "category": "external",
        "summary": "Microsoft Support Lifecycle",
        "url": "https://support.microsoft.com/lifecycle"
      },
      {
        "category": "external",
        "summary": "Common Vulnerability Scoring System",
        "url": "https://www.first.org/cvss"
      }
    ],
    "title": "qs.stringify crashes on null/undefined entries in comma-format arrays under encodeValuesOnly",
    "tracking": {
      "current_release_date": "2026-05-23T01:02:15.000Z",
      "generator": {
        "date": "2026-05-23T07:14:23.786Z",
        "engine": {
          "name": "MSRC Generator",
          "version": "1.0"
        }
      },
      "id": "msrc_CVE-2026-8723",
      "initial_release_date": "2026-05-02T00:00:00.000Z",
      "revision_history": [
        {
          "date": "2026-05-23T01:02:15.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        }
      ],
      "status": "final",
      "version": "1"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version",
                "name": "3.0",
                "product": {
                  "name": "Azure Linux 3.0",
                  "product_id": "17084"
                }
              }
            ],
            "category": "product_name",
            "name": "Azure Linux"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "azl3 python-tensorboard 0:2.16.2-6.azl3",
                "product": {
                  "name": "azl3 python-tensorboard 0:2.16.2-6.azl3",
                  "product_id": "1"
                }
              }
            ],
            "category": "product_name",
            "name": "python-tensorboard"
          }
        ],
        "category": "vendor",
        "name": "Microsoft"
      }
    ],
    "relationships": [
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "azl3 python-tensorboard 0:2.16.2-6.azl3 as a component of Azure Linux 3.0",
          "product_id": "17084-1"
        },
        "product_reference": "1",
        "relates_to_product_reference": "17084"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-8723",
      "cwe": {
        "id": "CWE-476",
        "name": "NULL Pointer Dereference"
      },
      "notes": [
        {
          "category": "general",
          "text": "harborist",
          "title": "Assigning CNA"
        }
      ],
      "product_status": {
        "known_affected": [
          "17084-1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2026-8723 qs.stringify crashes on null/undefined entries in comma-format arrays under encodeValuesOnly - VEX",
          "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-8723.json"
        }
      ],
      "remediations": [
        {
          "category": "none_available",
          "date": "2026-05-23T01:02:15.000Z",
          "details": "There is no fix available for this vulnerability as of now",
          "product_ids": [
            "17084-1"
          ]
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "environmentalsScore": 0.0,
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "temporalScore": 5.3,
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
            "version": "3.1"
          },
          "products": [
            "17084-1"
          ]
        }
      ],
      "title": "qs.stringify crashes on null/undefined entries in comma-format arrays under encodeValuesOnly"
    }
  ]
}

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.

Action not permitted

CVE-2026-8723 (GCVE-0-2026-8723)

FKIE_CVE-2026-8723

GHSA-Q8MJ-M7CP-5Q26

Summary

Details

PoC

Fix

Affected versions

Impact

MSRC_CVE-2026-8723

Tags

Sightings

Nomenclature