CVE-2026-59870 MEDIUM

CVE-2026-59870: js-yaml quadratic-complexity denial of service via YAML11_SCHEMA !!omap parsing

Vendor Nodeca
Product js-yaml
Weakness CWE-407
Published July 8, 2026
Last update July 8, 2026
View on NVD All CVEs

CVSS base score

5.3/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

July 8, 2026 CVE published