CVE-2026-59868
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 5.0.0 before 5.2.0, when merge keys are enabled, 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 version 5.2.0.
- Affected
- nodeca · js-yaml
- CVSS v3.1 NVD
- 7.5 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS v3.1 GITHUB
- 5.3 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - EPSS
- 0.64% chance of exploitation in the next 30 days, 50th percentile
- Published
- 2026-07-08
- Updated
- 2026-07-09
Proof-of-concept exploits (1)
Security advisories
- nodeca/js-yaml/security/advisories/GHSA-g796-fgmg-93mv
- nodeca/js-yaml/commit/3105455b81dee69e0fd36e09ac0b2ccfdb54adc1