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Vulnerability record · CVE-2026-59880 · published 8 July 2026

CVE-2026-59880: Immutable-js immutable vulnerability

Immutable Js · Immutable

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.

8.7 CVSS 4.0 High EPSS 0.66% · top 50.2% CWE-407 · CWE-407
8.7CVSS 4.0 base score
0.66%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References, 2 tagged exploit
10 Jul 2026Last modified by NVD

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.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
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
https://github.com/immutable-js/immutable-js/security/advisories/GHSA-xvcm-6775-5m9r ExploitMitigationVendor Advisory
https://github.com/immutable-js/immutable-js/security/advisories/GHSA-xvcm-6775-5m9r ExploitMitigationVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

8.7CVE-2026-59879Immutable-js immutable integer overflow vulnerabilityImmutable.js provides many Persistent Immutable data structures. Prior to 4.3.9 and 5.1.8, List#set, List#setSize, List#setIn, List#updateIn, and the…EPSS 0.66%8.7CVE-2026-29063Immutable-js immutable prototype pollution vulnerabilityImmutable.js provides many Persistent Immutable data structures. Prior to versions 3.8.3, 4.3.7, and 5.1.5, Prototype Pollution is possible in immuta…EPSS 1.2%

Source: NIST National Vulnerability Database (record CVE-2026-59880), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.