Nodeca: >> Js-Yaml >> 0.3.5 Security Vulnerabilities
js-yaml is a JavaScript YAML parser and dumper. Prior to 4.2.0 and 3.15.0, a crafted YAML document can trigger algorithmic CPU exhaustion in js-yaml merge-key processing (<<) by repeating the same alias many times in a merge sequence. This causes quadratic parse-time behavior relative to input size and can block a Node.js worker/event loop for seconds with a relatively small payload (tens of KB), resulting in denial of service. The issue is in merge handling inside lib/loader.js. This vulnerability is fixed in 4.2.0 and 3.15.0.
CVSS Score
5.3
EPSS Score
0.003
Published
2026-06-22
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).
CVSS Score
5.3
EPSS Score
0.004
Published
2025-11-13
The JS-YAML module before 2.0.5 for Node.js parses input without properly considering the unsafe !!js/function tag, which allows remote attackers to execute arbitrary code via a crafted string that triggers an eval operation.
CVSS Score
6.8
EPSS Score
0.172
Published
2013-06-28