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

js-yaml is a JavaScript YAML parser and dumper. Prior to 3.15.1, 4.3.1, and 5.2.1, YAML11SCHEMA 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 On^2 CPU consumption when yaml.load parses a crafted...

CVE-2026-59870

CVE-2026-59870 affects js-yaml prior to 5.2.1. The YAML11_SCHEMA’s handling of the !!omap tag in omap.ts performs a linear duplicate-key scan on each insertion, causing O(n^2) CPU usage when yaml.load() parses crafted ordered-map documents. Red Hat and NVD entries confirm this results in CPU-inte...