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Vulnerability · Published Nov 13, 2025 · Assigned by GitHub_M

CVE-2025-64718js-yaml has prototype pollution in merge (<<)

Medium 5.3

In plain English

A medium-severity prototype pollution in js-yaml from nodeca. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.3Medium
Exploit odds (30 days)0.4%top 63.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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).

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12node-js-yamlno fix listedDEBIAN-CVE-2025-64718
Debian:13node-js-yamlno fix listedDEBIAN-CVE-2025-64718
Debian:14node-js-yaml4.1.1+dfsg+~4.0.9-1DEBIAN-CVE-2025-64718
Ubuntu:22.04:LTSnode-js-yamlno fix listedUBUNTU-CVE-2025-64718
Ubuntu:24.04:LTSnode-js-yamlno fix listedUBUNTU-CVE-2025-64718
Ubuntu:25.10node-js-yamlno fix listedUBUNTU-CVE-2025-64718
Ubuntu:26.04:LTSnode-js-yamlno fix listedUBUNTU-CVE-2025-64718
Ubuntu:26.10node-js-yamlno fix listedUBUNTU-CVE-2025-64718
npmjs-yaml3.14.2GHSA-mh29-5h37-fv8m
npmjs-yaml4.1.1GHSA-mh29-5h37-fv8m

Affected products (as reported)

VendorProductVersions
nodeca js-yaml >= 4.0.0, < 4.1.1< 3.14.2

Weakness: CWE-1321 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

References