node-qs — security advisory
### Summary `qs.stringify` throws a `TypeError` when it serializes an object whose own `constructor` property has a truthy, non-callable `isBuffer` member. `utils.isBuffer` duck-types buffers by calling `obj.constructor.isBuffer(obj)` after checking only that the property is truthy, so a value such as `{ constructor: { isBuffer: "x" } }` makes the call throw `TypeError: obj.constructor.isBuffer is not a function`. ### Details `lib/stringify.js:127` calls `utils.isBuffer` on every non-primitive value it serializes. `utils.isBuffer` (`lib/utils.js:332`) reads `obj.constructor.isBuffer` and invokes it without verifying that it is a function. `constructor` and `isBuffer` are ordinary property names, so any object carrying them as own properties reaches the unchecked call. Such an object can be built from untrusted input. `qs.parse("x[constructor][isBuffer]=y", { plainObjects: true })` or `{ allowPrototypes: true }` keeps the `constructor` key as an own property (the default parse options drop it), and `JSON.parse("{\"a\":{\"constructor\":{\"isBuffer\":\"x\"}}}")` produces the same shape with no qs option involved. Express 4 with its default `query parser` setting and body-parser with `extended: true` both call `qs.parse` with `allowPrototypes: true`, so on those stacks `req.query` and `req.body` can carry the shape directly. #### PoC ```js var qs = require("qs"); qs.stringify(qs.parse("x[constructor][isBuffer]=y", { plainObjects: true })); qs.stringify(JSON.parse("{\"a\":{\"const
- 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-2026-82417
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 03:20 UTC · Revision 1
Source evidence
### Summary `qs.stringify` throws a `TypeError` when it serializes an object whose own `constructor` property has a truthy, non-callable `isBuffer` member. `utils.isBuffer` duck-types buffers by calling `obj.constructor.isBuffer(obj)` after checking only that the property is truthy, so a value such as `{ constructor: { isBuffer: "x" } }` makes the call throw `TypeError: obj.constructor.isBuffer is not a function`. ### Details `lib/stringify.js:127` calls `utils.isBuffer` on every non-primitive value it serializes. `utils.isBuffer` (`lib/utils.js:332`) reads `obj.constructor.isBuffer` and invokes it without verifying that it is a function. `constructor` and `isBuffer` are ordinary property names, so any object carrying them as own properties reaches the unchecked call. Such an object can be built from untrusted input. `qs.parse("x[constructor][isBuffer]=y", { plainObjects: true })` or `{ allowPrototypes: true }` keeps the `constructor` key as an own property (the default parse options drop it), and `JSON.parse("{\"a\":{\"constructor\":{\"isBuffer\":\"x\"}}}")` produces the same shape with no qs option involved. Express 4 with its default `query parser` setting and body-parser with `extended: true` both call `qs.parse` with `allowPrototypes: true`, so on those stacks `req.query` and `req.body` can carry the shape directly. #### PoC ```js var qs = require("qs"); qs.stringify(qs.parse("x[constructor][isBuffer]=y", { plainObjects: true })); qs.stringify(JSON.parse("{\"a\":{\"const
osv:UBUNTU-CVE-2026-82417
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": "62231656540105f4089bf7efe8daed100853fc7f07159b7e53eab0173a581818",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-82417",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-82417",
"summary": "### Summary `qs.stringify` throws a `TypeError` when it serializes an object whose own `constructor` property has a truthy, non-callable `isBuffer` member. `utils.isBuffer` duck-types buffers by calling `obj.constructor.isBuffer(obj)` after checking only that the property is truthy, so a value such as `{ constructor: { isBuffer: \"x\" } }` makes the call throw `TypeError: obj.constructor.isBuffer is not a function`. ### Details `lib/stringify.js:127` calls `utils.isBuffer` on every non-primitive value it serializes. `utils.isBuffer` (`lib/utils.js:332`) reads `obj.constructor.isBuffer` and invokes it without verifying that it is a function. `constructor` and `isBuffer` are ordinary property names, so any object carrying them as own properties reaches the unchecked call. Such an object can be built from untrusted input. `qs.parse(\"x[constructor][isBuffer]=y\", { plainObjects: true })` or `{ allowPrototypes: true }` keeps the `constructor` key as an own property (the default parse options drop it), and `JSON.parse(\"{\\\"a\\\":{\\\"constructor\\\":{\\\"isBuffer\\\":\\\"x\\\"}}}\")` produces the same shape with no qs option involved. Express 4 with its default `query parser` setting and body-parser with `extended: true` both call `qs.parse` with `allowPrototypes: true`, so on those stacks `req.query` and `req.body` can carry the shape directly. #### PoC ```js var qs = require(\"qs\"); qs.stringify(qs.parse(\"x[constructor][isBuffer]=y\", { plainObjects: true })); qs.stringify(JSON.parse(\"{\\\"a\\\":{\\\"const",
"evidence": "osv:UBUNTU-CVE-2026-82417",
"products": [
{
"name": {
"value": "node-qs",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.4.2-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.6.5-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.6.5-1ubuntu0.1~esm1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "node-qs",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2.2.4-1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "node-qs",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2.2.4-1",
"evidence": "/affected/2/versions"
},
{
"value": "2.2.4-1ubuntu1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "node-qs",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "6.5.2-1",
"evidence": "/affected/3/versions"
},
{
"value": "6.9.0+ds-1",
"evidence": "/affected/3/versions"
},
{
"value": "6.9.1+ds-1",
"evidence": "/affected/3/versions"
},
{
"value": "6.9.1+ds-1ubuntu0.1~esm1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "node-qs",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "6.9.4+ds-1",
"evidence": "/affected/4/versions"
},
{
"value": "6.10.1+ds-1",
"evidence": "/affected/4/versions"
},
{
"value": "6.10.2+ds+~6.9.7-1",
"evidence": "/affected/4/versions"
},
{
"value": "6.10.3+ds+~6.9.7-1",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "node-qs",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "6.11.0+ds+~6.9.7-3",
"evidence": "/affected/5/versions"
},
{
"value": "6.11.0+ds+~6.9.7-4",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "node-qs",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "6.14.1+ds+~6.14.0-1",
"evidence": "/affected/6/versions"
},
{
"value": "6.15.2+ds+~6.15.1-1",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "node-qs",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "6.13.0+ds+~6.9.16-1",
"evidence": "/affected/7/versions"
},
{
"value": "6.14.1+ds+~6.14.0-1",
"evidence": "/affected/7/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "UBUNTU-CVE-2026-82417",
"aliases": [
"UBUNTU-CVE-2026-82417"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/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"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "node-qs",
"purl": "pkg:deb/ubuntu/node-qs?arch=source&distro=esm-infra-legacy%2Ftrusty",
"ecosystem": "Ubuntu:Pro:14.04:LTS"
},
"versions": [
"0.4.2-1",
"0.6.5-1",
"0.6.5-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-82417.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "node-qs",
"binary_version": "0.6.5-1ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "node-qs",
"purl": "pkg:deb/ubuntu/node-qs?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"2.2.4-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-82417.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "node-qs",
"binary_version": "2.2.4-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "node-qs",
"purl": "pkg:deb/ubuntu/node-qs?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
"2.2.4-1",
"2.2.4-1ubuntu1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-82417.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "node-qs",
"binary_version": "2.2.4-1ubuntu1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "node-qs",
"purl": "pkg:deb/ubuntu/node-qs?arch=source&distro=esm-apps%2Ffocal",
"ecosystem": "Ubuntu:Pro:20.04:LTS"
},
"versions": [
"6.5.2-1",
"6.9.0+ds-1",
"6.9.1+ds-1",
"6.9.1+ds-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-82417.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "node-qs",
"binary_version": "6.9.1+ds-1ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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],
"package": {
"name": "node-qs",
"purl": "pkg:deb/ubuntu/node-qs?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"6.9.4+ds-1",
"6.10.1+ds-1",
"6.10.2+ds+~6.9.7-1",
"6.10.3+ds+~6.9.7-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-82417.json"
},
"ecosystem_specific": {
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"ecosystem": "Ubuntu:24.04:LTS"
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"versions": [
"6.11.0+ds+~6.9.7-3",
"6.11.0+ds+~6.9.7-4"
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"ecosystem_specific": {
"binaries": [
{
"binary_name": "node-qs",
"binary_version": "6.11.0+ds+~6.9.7-4"
}
]
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},
{
"ranges": [
{
"type": "ECOSYSTEM",
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{
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"package": {
"name": "node-qs",
"purl": "pkg:deb/ubuntu/node-qs?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"6.14.1+ds+~6.14.0-1",
"6.15.2+ds+~6.15.1-1"
],
"database_specific": {
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},
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"binaries": [
{
"binary_name": "node-qs",
"binary_version": "6.15.2+ds+~6.15.1-1"
}
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},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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}
]
}
],
"package": {
"name": "node-qs",
"purl": "pkg:deb/ubuntu/node-qs?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"6.13.0+ds+~6.9.16-1",
"6.14.1+ds+~6.14.0-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-82417.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "node-qs",
"binary_version": "6.14.1+ds+~6.14.0-1"
}
]
}
}
],
"modified": "2026-10-17T13:01:11.350257529Z",
"provider": "osv",
"upstream": [
"CVE-2026-82417"
],
"references": [
"https://ubuntu.com/security/CVE-2026-82417",
"https://www.cve.org/CVERecord?id=CVE-2026-82417",
"https://github.com/ljharb/qs/security/advisories/GHSA-4mjr-xmp4-gh2g",
"https://github.com/ljharb/qs/commit/e83d321ffafb38cf210683ac31714fce6ce1c6c6"
]
},
"related_cves": [
{
"value": "CVE-2026-82417",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/1/score"
},
"source_id": "core-osv",
"document_id": 361176,
"published_at": "2026-08-30T00:16:00+00:00"
}