Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Nodeca | Js-Yaml | >= 5.0.0, < 5.2.1 |
Related Weaknesses (CWE)
References
- https://github.com/nodeca/js-yaml/commit/39f3211a2f01b3c6982710cf21434ab7060acefPatch
- https://github.com/nodeca/js-yaml/releases/tag/5.2.1Release Notes
- https://github.com/nodeca/js-yaml/security/advisories/GHSA-724g-mxrg-4qvmExploitVendor Advisory
- https://github.com/nodeca/js-yaml/security/advisories/GHSA-724g-mxrg-4qvmExploitVendor Advisory
FAQ
What is CVE-2026-59870?
CVE-2026-59870 is a vulnerability with a CVSS score of 5.3 (MEDIUM). 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 s...
How severe is CVE-2026-59870?
CVE-2026-59870 has been rated MEDIUM with a CVSS base score of 5.3/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-59870?
Check the references section above for vendor advisories and patch information. Affected products include: Nodeca Js-Yaml.