node-qs — security advisory
### 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 wi
- 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-2026-2391
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:58 UTC · Revision 1
Source evidence
### 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 wi
osv:UBUNTU-CVE-2026-2391
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": "61b4d3697aab267e77f5d95f3e4acfe3fb5f6cdeddf43be9b8294482d5ff75f4",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-2391",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-2391",
"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 wi",
"evidence": "osv:UBUNTU-CVE-2026-2391",
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"aliases": [
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],
"metrics": [
{
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"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L"
},
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
},
{
"type": "CVSS_V4",
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"versions": [
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],
"modified": "2026-10-17T12:59:56.387161176Z",
"provider": "osv",
"upstream": [
"CVE-2026-2391"
],
"references": [
"https://ubuntu.com/security/CVE-2026-2391",
"https://www.cve.org/CVERecord?id=CVE-2026-2391",
"https://github.com/ljharb/qs/security/advisories/GHSA-w7fw-mjwx-w883",
"https://github.com/ljharb/qs/commit/f6a7abff1f13d644db9b05fe4f2c98ada6bf8482"
]
},
"related_cves": [
{
"value": "CVE-2026-2391",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/1/score"
},
"source_id": "core-osv",
"document_id": 360002,
"published_at": "2026-02-12T05:17:00+00:00"
}