CVE-2026-59880Immutable.js: Hash-collision algorithmic complexity denial of service in Immutable.Map/Set

Description

Immutable.js provides many Persistent Immutable data structures. Prior to 4.3.9 and 5.1.8, Immutable.Map and Immutable.Set keep keys that share the same 32-bit hash in a HashCollisionNode collision bucket that is scanned linearly, allowing an attacker who controls keys inserted into a Map, such as through Immutable.Map(obj), Immutable.fromJS(obj), state.merge(userObject), or mergeDeep, to craft many colliding keys and degrade insertion and lookup to consume disproportionate CPU. This issue is fixed in versions 4.3.9 and 5.1.8.

Data: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Published as the sources state it, in English.

Affected products and versions

References and patches

• https://github.com/immutable-js/immutable-js/security/advisories/GHSA-xvcm-6775-5m9r ExploitMitigationVendor Advisory
• https://github.com/immutable-js/immutable-js/commit/3dd7e5655012597a41873e328bf9142a8901527b Patch
• https://github.com/immutable-js/immutable-js/commit/e51d49fc612ded5ec4dfb94ff294d22074269b0f Patch
• https://github.com/immutable-js/immutable-js/releases/tag/v4.3.9 Release Notes
• https://github.com/immutable-js/immutable-js/releases/tag/v5.1.8 Release Notes