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.
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-52cp-r559-cp3m js-yaml: YAML merge-key chains can force quadratic CPU consumption
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Wed, 15 Jul 2026 00:15:00 +0000

Type Values Removed Values Added
First Time appeared Redhat
Redhat hummingbird
Weaknesses CWE-606
CPEs cpe:/a:redhat:hummingbird:1
Vendors & Products Redhat
Redhat hummingbird
References
Metrics threat_severity

None

threat_severity

Important


Thu, 09 Jul 2026 16:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 08 Jul 2026 17:00:00 +0000

Type Values Removed Values Added
First Time appeared Nodeca
Nodeca js-yaml
Vendors & Products Nodeca
Nodeca js-yaml

Wed, 08 Jul 2026 15:45:00 +0000

Type Values Removed Values Added
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.
Title js-yaml: YAML merge-key chains can force quadratic CPU consumption
Weaknesses CWE-407
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-09T15:14:29.753Z

Reserved: 2026-07-07T15:41:53.607Z

Link: CVE-2026-59869

cve-icon Vulnrichment

Updated: 2026-07-09T15:14:24.071Z

cve-icon NVD

Status : Analyzed

Published: 2026-07-08T16:16:33.423

Modified: 2026-07-13T15:05:34.130

Link: CVE-2026-59869

cve-icon Redhat

Severity : Important

Publid Date: 2026-07-08T15:15:54Z

Links: CVE-2026-59869 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-07-31T14:00:07Z

Weaknesses