CVE-2026-59869
js-yaml: YAML merge-key chains can force quadratic CPU consumption
HIGH 7.5EPSS 0.6%
js-yaml is a JavaScript YAML parser and dumper. From 3.0.0 before 3.15.0 and from 4.0.0 before 4.3.0, js-yaml can spend quadratic CPU time parsing a document whose size grows only linearly when a chain of mappings uses merge keys where each mapping merges the previous one. This issue is fixed in versions 3.15.0 and 4.3.0.
- Affected
- nodeca · js-yaml
- CVSS v3.1 GITHUB
- 7.5 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS
- 0.58% chance of exploitation in the next 30 days, 47th percentile
- Published
- 2026-07-08
- Updated
- 2026-07-09
Proof-of-concept exploits (1)
Security advisories
- nodeca/js-yaml/security/advisories/GHSA-52cp-r559-cp3m
- nodeca/js-yaml/commit/24f13e79ee1343a7e30bd6f6c9d9cdbf0ac9b2b7