CVE-2026-59870

mediumCVSS 5.3covered by 1 sourcefirst seen 2026-07-08

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.

⚡ Watch CVE-2026-59870

Get an email if CVE-2026-59870 is added to CISA KEV, gains public exploit code, or a new advisory cites it — max one per day, one-click unsubscribe.

Exploitation outlook

Low exploitation risk0.36% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 28% of all EPSS-scored CVEs.

Advisory coverage (1)

mediumCVE-2026-59870: js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 before 5.2.1, YAML11_SCHEMA support…nvd · 2026-07-08

External references

NVD record for CVE-2026-59870

CVE.org record

Embed the live status

— this badge updates automatically when the KEV or exploit status changes. How to embed it →

[![CVE-2026-59870 status](https://www.csirts.com/badge/CVE-2026-59870)](https://www.csirts.com/cve/CVE-2026-59870)