CVE-2026-59880

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.

Weakness Type (CWE)

CWE-407 CWE-407

References

Other References

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

Frequently Asked Questions

What is CVE-2026-59880? +

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.

How do I check if I'm vulnerable to CVE-2026-59880? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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