CVE-2026-59870

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 Reserved 2026-07-07 | Published 2026-07-08 | Updated 2026-07-08 | Assigner GitHub_M

Problem types

CWE-407: Inefficient Algorithmic Complexity

Product status

References

github.com/...s-yaml/security/advisories/GHSA-724g-mxrg-4qvm exploit

github.com/...s-yaml/security/advisories/GHSA-724g-mxrg-4qvm

github.com/...ommit/39f3211a2f01b3c6982710cf21434ab7060acefe

github.com/nodeca/js-yaml/releases/tag/5.2.1

cve.org (CVE-2026-59870)

nvd.nist.gov (CVE-2026-59870)

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