CVE-2026-59869: js-yaml: YAML merge-key chains can force quadratic CPU consumption
High · CVSS 7.5 (CVSS 3.1)EPSS 0.58%, 48th percentilePublished Updated Assigner: GitHub_M
Description
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.
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H · CWE-407
Tracked companies
Mapped from the CVE’s affected-product data, NVD CPE matches, vendor advisories or package feeds. A mapping means the vendor’s software is named, not that its hosted service was exposed.
Status incidents that name it
No tracked status incident names this CVE.
Affected vendors and products
nodeca: js-yaml
References
- CVE record on cve.org (opens in new tab)
- NVD entry (opens in new tab)
- github.com/nodeca/js-yaml/commit/24f13e79ee1343a7e30bd6f6c9d9cdbf0ac9b2b7 (opens in new tab)
- github.com/nodeca/js-yaml/commit/59423c6f8cdc78742ac00e25a4dd39ef16b702e4 (opens in new tab)
- github.com/nodeca/js-yaml/releases/tag/3.15.0 (opens in new tab)
- github.com/nodeca/js-yaml/releases/tag/4.3.0 (opens in new tab)
- github.com/nodeca/js-yaml/security/advisories/GHSA-52cp-r559-cp3m (opens in new tab)
- CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (opens in new tab)
- This product uses data from the NVD API but is not endorsed or certified by the NVD. (opens in new tab)
- Known Exploited Vulnerabilities catalog from CISA. (opens in new tab)
- EPSS scores from FIRST (Exploit Prediction Scoring System). (opens in new tab)