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CVE record

CVE-2025-64718

js-yaml has prototype pollution in merge (<<)

js-yaml is a JavaScript YAML parser and dumper. In js-yaml before 4.1.1 and 3.14.2, it's possible for an attacker to modify the prototype of the result of a parsed yaml document via prototype pollution (`__proto__`). All users who parse untrusted yaml documents may be impacted. The problem is patched in js-yaml 4.1.1 and 3.14.2. Users can protect against this kind of attack on the server by using `node --disable-proto=delete` or `deno` (in Deno, pollution protection is on by default).

CVE evidence

Known exploitation

Not listed in fetched KEV catalog

Absence from the fetched catalog does not establish that exploitation has not occurred.

Severity

moderate

CVSS 5.3 ยท CVSS_V3

Affected packages

1

Supported package records returned by OSV. Vendor and product names are not used to infer matches.

OSV package mapping

Affected open-source packages

PackageEcosystemFixed versions
js-yamlnpm4.1.1, 3.14.2