Vulnerability Description
js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 until 5.2.2, parsing a small YAML document can take exponential time when an application calls load() or loadAll() on untrusted input. In src/parser/parser.ts, readFlowCollection uses restoreState and calls parseNode a second time when a flow-sequence entry is recognized as a key: value pair. If the key is a nested flow sequence of the same shape, every level is parsed twice, causing O(2^n) work and allowing an input under 200 bytes to keep one CPU busy for minutes, block the Node.js event loop, and stall the process. No anchors, aliases, merges, tags, or nondefault options are required. This issue is fixed in version 5.2.2.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/nodeca/js-yaml/commit/3e5240f9cbe645ce5afb58524954a13c8539c85
- https://github.com/nodeca/js-yaml/security/advisories/GHSA-pm4m-ph32-ghv5
- https://github.com/nodeca/js-yaml/security/advisories/GHSA-pm4m-ph32-ghv5
FAQ
What is CVE-2026-73643?
CVE-2026-73643 is a vulnerability with a CVSS score of 7.5 (HIGH). js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 until 5.2.2, parsing a small YAML document can take exponential time when an application calls load() or loadAll() on untrusted input. In src...
How severe is CVE-2026-73643?
CVE-2026-73643 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-2026-73643?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.