Prototype Pollution in Nodeca Js-Yaml
CVE-2025-64718
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).
Vulnerability class: Prototype Pollution
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (32.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 32nd percentile — 32.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Nodeca Js-Yaml — versions >= 4.0.0, < 4.1.1, < 3.14.2
Weakness classification (CWE)
References
- github.com/nodeca/js-yaml/security/advisories/GHSA-mh29-5h37-fv8m (Vendor Advisory)
- github.com/nodeca/js-yaml/issues/730 (Issue Tracking)
- github.com/nodeca/js-yaml/commit/383665ff4248ec2192d1274e934462bb30426879 (Patch)
- github.com/nodeca/js-yaml/commit/5278870a17454fe8621dbd8c445c412529525266 (Patch)
- af854a3a-2127-422b-91ae-364da2661108 (Vendor Advisory)
Frequently asked questions
- What is CVE-2025-64718?
- CVE-2025-64718 is a medium-severity vulnerability in Nodeca Js-Yaml, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 5.3/10. Published 2025-11-13.
- How severe is CVE-2025-64718?
- Medium severity. CVSS v3 base score is 5.3 out of 10.