CVE-2025-64718

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

Published Nov 13, 2025 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
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).

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-mh29-5h37-fv8m js-yaml has prototype pollution in merge (<<)
History
Type Values Removed Values Added
Description js-yaml is a JavaScript YAML parser and dumper. In js-yaml 4.1.0 and below, 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. 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). 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).
References
Type Values Removed Values Added
First Time appeared Nodeca
Nodeca js-yaml
CPEs cpe:2.3:a:nodeca:js-yaml:*:*:*:*:*:node.js:*:*
Vendors & Products Nodeca
Nodeca js-yaml
Type Values Removed Values Added
First Time appeared Js-yaml
Js-yaml js-yaml
Vendors & Products Js-yaml
Js-yaml js-yaml
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description js-yaml is a JavaScript YAML parser and dumper. In js-yaml 4.1.0 and below, 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. 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).
Title js-yaml has prototype pollution in merge (<<)
Weaknesses CWE-1321
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jan 29, 2026, 10:08 PM
Reserved
Nov 10, 2025, 2:07 PM
Status
Analyzed
Published
Nov 13, 2025, 4:15 PM
Modified
Oct 7, 2026, 9:10 PM
Severity
Moderate
Public date
Nov 13, 2025, 3:32 PM