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).
Published: 2025-11-13
Score: 5.3 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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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

Thu, 29 Jan 2026 22:15:00 +0000

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

Wed, 21 Jan 2026 15:30:00 +0000

Type Values Removed Values Added
References

Tue, 16 Dec 2025 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Tue, 02 Dec 2025 19:45:00 +0000

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

Fri, 14 Nov 2025 09:30:00 +0000

Type Values Removed Values Added
First Time appeared Js-yaml
Js-yaml js-yaml
Vendors & Products Js-yaml
Js-yaml js-yaml

Thu, 13 Nov 2025 17:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

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


Thu, 13 Nov 2025 15:45:00 +0000

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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-01-29T22:08:30.431Z

Reserved: 2025-11-10T14:07:42.922Z

Link: CVE-2025-64718

cve-icon Vulnrichment

Updated: 2026-01-21T14:38:16.644Z

cve-icon NVD

Status : Analyzed

Published: 2025-11-13T16:15:57.153

Modified: 2026-02-02T12:54:45.340

Link: CVE-2025-64718

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-11-13T15:32:44Z

Links: CVE-2025-64718 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-11-14T09:28:09Z

Weaknesses