node-qs — security advisory
### Summary When `qs.parse` is called with `comma: true` and `throwOnLimitExceeded: true`, a comma-separated value under a bracket-push key (`a[]=1,2,3,4`) is split into an array without being compared against `arrayLimit`, while the same value under a flat key (`a=1,2,3,4`), an indexed key (`a[0]=`), a nested key (`a[b]=`), or a dotted key (`a.b=` with `allowDots`) throws the documented `RangeError`. A single parameter such as `a[]=1,2,2,...` therefore produces an inner array of arbitrary length even though the caller opted into the hard limit. This is the `[]=` key form that the fix for CVE-2026-2391 (qs 6.14.2) did not cover. ### Details In `lib/parse.js`, a comma-separated value under a `[]=` key is split and then wrapped as a single nested element (`val = [val]`, so that each `a[]=x,y` group counts as one element of the outer array). The `arrayLimit` check that 6.14.2 added for comma values runs after that wrap, so for `[]=` parts it only ever saw the wrapper of length 1. 6.15.3 added a pre-split comma count so that an oversized value throws before it is allocated, but gated it on an `isFlatArrayValue` flag that `parseValues` set to `false` for any part containing `[]=`, and did not pass it for object-valued input, so the gap remained. #### PoC ```js var qs = require('qs'); var options = { comma: true, arrayLimit: 3, throwOnLimitExceeded: true }; qs.parse('a=1,2,3,4', options); // RangeError: Array limit exceeded. Only 3 elements allowed in an array. qs.parse('a[]=1,2,3,
- 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-2026-82562
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 03:21 UTC · Revision 1
Source evidence
### Summary When `qs.parse` is called with `comma: true` and `throwOnLimitExceeded: true`, a comma-separated value under a bracket-push key (`a[]=1,2,3,4`) is split into an array without being compared against `arrayLimit`, while the same value under a flat key (`a=1,2,3,4`), an indexed key (`a[0]=`), a nested key (`a[b]=`), or a dotted key (`a.b=` with `allowDots`) throws the documented `RangeError`. A single parameter such as `a[]=1,2,2,...` therefore produces an inner array of arbitrary length even though the caller opted into the hard limit. This is the `[]=` key form that the fix for CVE-2026-2391 (qs 6.14.2) did not cover. ### Details In `lib/parse.js`, a comma-separated value under a `[]=` key is split and then wrapped as a single nested element (`val = [val]`, so that each `a[]=x,y` group counts as one element of the outer array). The `arrayLimit` check that 6.14.2 added for comma values runs after that wrap, so for `[]=` parts it only ever saw the wrapper of length 1. 6.15.3 added a pre-split comma count so that an oversized value throws before it is allocated, but gated it on an `isFlatArrayValue` flag that `parseValues` set to `false` for any part containing `[]=`, and did not pass it for object-valued input, so the gap remained. #### PoC ```js var qs = require('qs'); var options = { comma: true, arrayLimit: 3, throwOnLimitExceeded: true }; qs.parse('a=1,2,3,4', options); // RangeError: Array limit exceeded. Only 3 elements allowed in an array. qs.parse('a[]=1,2,3,
osv:UBUNTU-CVE-2026-82562
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": "7b10a65ee5f152839c1b9dddc81729fbbe4c7ebe2af98d27d66256cf1cf6c78d",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-82562",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-82562",
"summary": "### Summary When `qs.parse` is called with `comma: true` and `throwOnLimitExceeded: true`, a comma-separated value under a bracket-push key (`a[]=1,2,3,4`) is split into an array without being compared against `arrayLimit`, while the same value under a flat key (`a=1,2,3,4`), an indexed key (`a[0]=`), a nested key (`a[b]=`), or a dotted key (`a.b=` with `allowDots`) throws the documented `RangeError`. A single parameter such as `a[]=1,2,2,...` therefore produces an inner array of arbitrary length even though the caller opted into the hard limit. This is the `[]=` key form that the fix for CVE-2026-2391 (qs 6.14.2) did not cover. ### Details In `lib/parse.js`, a comma-separated value under a `[]=` key is split and then wrapped as a single nested element (`val = [val]`, so that each `a[]=x,y` group counts as one element of the outer array). The `arrayLimit` check that 6.14.2 added for comma values runs after that wrap, so for `[]=` parts it only ever saw the wrapper of length 1. 6.15.3 added a pre-split comma count so that an oversized value throws before it is allocated, but gated it on an `isFlatArrayValue` flag that `parseValues` set to `false` for any part containing `[]=`, and did not pass it for object-valued input, so the gap remained. #### PoC ```js var qs = require('qs'); var options = { comma: true, arrayLimit: 3, throwOnLimitExceeded: true }; qs.parse('a=1,2,3,4', options); // RangeError: Array limit exceeded. Only 3 elements allowed in an array. qs.parse('a[]=1,2,3,",
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"aliases": [
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"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L"
},
{
"type": "CVSS_V4",
"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"
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},
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"6.9.0+ds-1",
"6.9.1+ds-1",
"6.9.1+ds-1ubuntu0.1~esm1"
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],
"modified": "2026-10-17T13:01:11.606659799Z",
"provider": "osv",
"upstream": [
"CVE-2026-82562"
],
"references": [
"https://ubuntu.com/security/CVE-2026-82562",
"https://www.cve.org/CVERecord?id=CVE-2026-82562",
"https://github.com/ljharb/qs/security/advisories/GHSA-x5fp-wj9c-mxmx",
"https://github.com/ljharb/qs/commit/8859c37470e11b42b547b275e4e9bd0bc8cc5464",
"https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883"
]
},
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{
"value": "CVE-2026-82562",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/1/score"
},
"source_id": "core-osv",
"document_id": 361190,
"published_at": "2026-08-30T01:20:00+00:00"
}