Vulnerability Description
js-yaml is a JavaScript YAML parser and dumper. From 3.0.0 until 3.15.2 and 4.3.2, maxTotalMergeKeys in lib/js-yaml/loader.js and lib/loader.js does not count empty mapping sources while processing the merge key <<. An attacker can alias a large sequence of empty mappings into many merge targets, causing O(N * K) processing while totalMergeKeys remains unchanged and the configured resource limit is never reached. A relatively small YAML document can therefore cause prolonged CPU consumption in applications that parse untrusted YAML, and merge processing is enabled by default on these release lines. This issue is fixed in versions 3.15.2 and 4.3.2.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/nodeca/js-yaml/commit/3485bc06ff8a0251505f44a00414d90df246663
- https://github.com/nodeca/js-yaml/commit/6a8e05f9a485188ed730ac81e81ae221352ef48
- https://github.com/nodeca/js-yaml/commit/d90b6612a5a84385bdcb556c44578eac76dc0f6
- https://github.com/nodeca/js-yaml/pull/797
- https://github.com/nodeca/js-yaml/releases/tag/3.15.2
- https://github.com/nodeca/js-yaml/releases/tag/4.3.2
- https://github.com/nodeca/js-yaml/security/advisories/GHSA-2883-xcg3-v3hh
FAQ
What is CVE-2026-84375?
CVE-2026-84375 is a vulnerability with a CVSS score of 7.5 (HIGH). js-yaml is a JavaScript YAML parser and dumper. From 3.0.0 until 3.15.2 and 4.3.2, maxTotalMergeKeys in lib/js-yaml/loader.js and lib/loader.js does not count empty mapping sources while processing th...
How severe is CVE-2026-84375?
CVE-2026-84375 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-84375?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.