node-qs — security advisory
### 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 re
- Products
- node-qs
- Affected versions
- 0.4.2-1, 0.6.5-1, 0.6.5-1ubuntu0.1~esm1, 2.2.4-1, 2.2.4-1ubuntu1, 6.10.1+ds-1, 6.10.2+ds+~6.9.7-1, 6.10.3+ds+~6.9.7-1, 6.11.0+ds+~6.9.7-3, 6.11.0+ds+~6.9.7-4, 6.13.0+ds+~6.9.16-1, 6.14.1+ds+~6.14.0-1, 6.15.2+ds+~6.15.1-1, 6.5.2-1, 6.9.0+ds-1, 6.9.1+ds-1, 6.9.1+ds-1ubuntu0.1~esm1, 6.9.4+ds-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-8723
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 03:24 UTC · Revision 1
Source evidence
### 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 re
osv:UBUNTU-CVE-2026-8723
node-qs
Fixed versions: Not specified
node-qs
Fixed versions: Not specified
node-qs
Fixed versions: Not specified
node-qs
Fixed versions: Not specified
node-qs
Fixed versions: Not specified
node-qs
Fixed versions: Not specified
node-qs
Fixed versions: Not specified
node-qs
Fixed versions: Not specified
node-qs
Fixed versions: Not specified
Complete source record
{
"id": "fc6eb2c58d52344835afe2b7d4b793b00d7dfc113b8523f81750fea8a70b31c6",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-8723",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-8723",
"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 re",
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"modified": "2026-10-17T13:01:14.264945332Z",
"provider": "osv",
"upstream": [
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],
"references": [
"https://ubuntu.com/security/CVE-2026-8723",
"https://www.cve.org/CVERecord?id=CVE-2026-8723",
"https://github.com/ljharb/qs/security/advisories/GHSA-q8mj-m7cp-5q26",
"https://github.com/ljharb/qs/commit/21f80b33e5c8b3f7eba1034fff0da4a4a37a1d41"
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"source_id": "core-osv",
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"published_at": "2026-05-17T00:16:00+00:00"
}