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).
https://github.com/advisories/GHSA-mh29-5h37-fv8m
https://github.com/nodeca/js-yaml/security/advisories/GHSA-mh29-5h37-fv8m
https://github.com/nodeca/js-yaml/issues/730#issuecomment-3549635876
https://github.com/nodeca/js-yaml/commit/5278870a17454fe8621dbd8c445c412529525266
https://github.com/nodeca/js-yaml/commit/383665ff4248ec2192d1274e934462bb30426879