Resource exhaustion in Nodeca Js-Yaml
CVE-2026-59870
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.007 (53.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 53.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.007 · change: +0.001
Affected products
- Nodeca Js-Yaml — versions >= 3.0.0, < 3.15.1, >= 5.0.0, < 5.2.1, >= 4.0.0, < 4.3.1
Weakness classification (CWE)
References
- github.com/nodeca/js-yaml/security/advisories/GHSA-724g-mxrg-4qvm (Exploit, Vendor Advisory)
- github.com/nodeca/js-yaml/commit/39f3211a2f01b3c6982710cf21434ab7060acefe (Patch)
- github.com/nodeca/js-yaml/releases/tag/5.2.1 (Release Notes)
- github.com/nodeca/js-yaml/commit/22a8071ef032117bc6249c330b240ac3aa2d3ded
- github.com/nodeca/js-yaml/commit/c3cc4b0bb9ddb9af2dd9b61e0d56f5ce7983cd4a
- github.com/nodeca/js-yaml/releases/tag/3.15.1
- github.com/nodeca/js-yaml/releases/tag/4.3.1
Frequently asked questions
- What is CVE-2026-59870?
- CVE-2026-59870 is a high-severity vulnerability in Nodeca Js-Yaml, classified under Inefficient Algorithmic Complexity. CVSS score: 7.5/10. Published 2026-07-08.
- How severe is CVE-2026-59870?
- High severity. CVSS v3 base score is 7.5 out of 10.