Description
js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 before 5.2.1, YAML11_SCHEMA support for the !!omap tag in src/tag/sequence/omap.ts uses omapTag.addItem() to perform a linear duplicate-key scan on every insertion, causing O(n^2) CPU consumption when yaml.load() parses a crafted ordered-map document. This issue is fixed in version 5.2.1.
Published: 2026-07-08
Score: 5.3 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

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

Type Values Removed Values Added
Description js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 before 5.2.1, YAML11_SCHEMA support for the !!omap tag in src/tag/sequence/omap.ts uses omapTag.addItem() to perform a linear duplicate-key scan on every insertion, causing O(n^2) CPU consumption when yaml.load() parses a crafted ordered-map document. This issue is fixed in version 5.2.1.
Title js-yaml quadratic-complexity denial of service via YAML11_SCHEMA !!omap parsing
Weaknesses CWE-407
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-08T15:50:55.378Z

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

Link: CVE-2026-59870

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses