CVE-2026-59880

CVE-2026-59880 is a high-severity vulnerability with a CVSS 4.0 base score of 8.7. The underlying weakness is classified as CWE-407.

Key facts

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.

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 severe is CVE-2026-59880?
CVE-2026-59880 has a CVSS 4.0 base score of 8.7, rated high severity.
Is CVE-2026-59880 being actively exploited?
It is not currently listed in CISA's Known Exploited Vulnerabilities catalog, and no EPSS exploit-prediction score is available yet.
How do I fix CVE-2026-59880?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-59880 published?
CVE-2026-59880 was published on 2026-07-08.

References

Other CWE-407 vulnerabilities

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