CVE-2026-59870
js-yaml is a JavaScript YAML parser and dumper.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.74%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
js-yaml is a JavaScript YAML parser and dumper. Prior to 3.15.1, 4.3.1, and 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. In v3 and v4, !!omap is active and exploitable by default. v5 doesn't use !!omap by default, and the chances of activating it are very low.This issue is fixed in 3.15.1, 4.3.1, and 5.2.1.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.74% probability · 54th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-407, CWE-770
- Affected
- nodeca/js-yaml
- Source
- security-advisories@github.com
EPSS 0.7% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://github.com/nodeca/js-yaml/commit/22a8071ef032117bc6249c330b240ac3aa2d3ded
- https://github.com/nodeca/js-yaml/commit/39f3211a2f01b3c6982710cf21434ab7060acefePatch
- https://github.com/nodeca/js-yaml/commit/c3cc4b0bb9ddb9af2dd9b61e0d56f5ce7983cd4a
- https://github.com/nodeca/js-yaml/releases/tag/3.15.1
- https://github.com/nodeca/js-yaml/releases/tag/4.3.1
- https://github.com/nodeca/js-yaml/releases/tag/5.2.1Release Notes
- https://github.com/nodeca/js-yaml/security/advisories/GHSA-724g-mxrg-4qvmExploit, Vendor Advisory
- https://github.com/nodeca/js-yaml/security/advisories/GHSA-724g-mxrg-4qvmExploit, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.