CVE-2025-64718: nodeca js-yaml Prototype Pollution

Vulnerability summary

CVE-2025-64718 is a medium (CVSS 5.3) Prototype Pollution vulnerability in nodeca js-yaml. EPSS estimates a 0.42% chance of exploitation in the next 30 days, higher than 35.2% of scored vulnerabilities.

Timeline

1. 13-11-2025
   PublishedVulnerability first disclosed.
2. 29-01-2026
   Last modifiedVulnerability information updated.

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).

• CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.