GHSA-724G-MXRG-4QVM js-yaml: Quadratic-complexity (O(n^2)) DoS via !!omap tag in YAML11_SCHEMA

Summary js-yaml v5.x introduces YAML11SCHEMA support with the !!omap ordered map tag. The omapTag.addItem function performs a linear On scan for duplicate key detection on every insertion, resulting in On^2 total time to parse a document with n omap entries. An attacker can send a small crafted...

Inefficient Algorithmic Complexity

Overview js-yaml is a human-friendly data serialization language. Affected versions of this package are vulnerable to Inefficient Algorithmic Complexity in merge key handling during YAML parsing, where each mapping in a chain re-enumerates the keys inherited from the previous mapping. An attacker...

CVE-2026-59870

js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 before 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 ordered-map...

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

js-yaml is a JavaScript YAML parser and dumper. From 5.0.0 before 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 ordered-map...