medium5.3
CVE-2025-64718
js-yaml has prototype pollution in merge (<<)
Impact
### Impact In js-yaml 4.1.0, 4.0.0, and 3.14.1 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. ### Patches Problem is patched in js-yaml 4.1.1 and 3.14.2. ### Workarounds You 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 https://cheatsheetseries.owasp.org/cheatsheets/Prototype_Pollution_Prevention_Cheat_Sheet.html
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | js-yaml | >= 4.0.0, < 4.1.1 | 4.1.1 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Nodeca | Js-Yaml | before 3.14.2 from 4.0.0 before 4.1.1 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/nodeca/js-yaml/commit/383665ff4248ec2192d1274e934462bb30426879
- https://github.com/nodeca/js-yaml/commit/5278870a17454fe8621dbd8c445c412529525266
- https://github.com/nodeca/js-yaml/issues/730#issuecomment-3549635876
- https://github.com/nodeca/js-yaml/security/advisories/GHSA-mh29-5h37-fv8m
- https://github.com/advisories/GHSA-mh29-5h37-fv8m
- https://nvd.nist.gov/vuln/detail/CVE-2025-64718