Vulnerability · Published Jul 8, 2026 · Assigned by GitHub_M
CVE-2026-59880Immutable.js: Hash-collision algorithmic complexity denial of service in Immutable.Map/Set
High 8.7
In plain English
A high-severity security flaw in immutable-js from immutable-js. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 52% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | node-immutable | no fix listed | DEBIAN-CVE-2026-59880 |
| Debian:13 | node-immutable | no fix listed | DEBIAN-CVE-2026-59880 |
| Debian:14 | node-immutable | 4.3.9-1 | DEBIAN-CVE-2026-59880 |
| Ubuntu:22.04:LTS | node-immutable | no fix listed | UBUNTU-CVE-2026-59880 |
| Ubuntu:24.04:LTS | node-immutable | no fix listed | UBUNTU-CVE-2026-59880 |
| Ubuntu:25.10 | node-immutable | no fix listed | UBUNTU-CVE-2026-59880 |
| Ubuntu:26.04:LTS | node-immutable | no fix listed | UBUNTU-CVE-2026-59880 |
| Ubuntu:26.10 | node-immutable | no fix listed | UBUNTU-CVE-2026-59880 |
| npm | immutable | 3.8.4 | GHSA-xvcm-6775-5m9r |
| npm | immutable | 4.3.9 | GHSA-xvcm-6775-5m9r |
| npm | immutable | 5.1.8 | GHSA-xvcm-6775-5m9r |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| immutable-js | immutable-js | < 4.3.9>= 5.0.0-beta.1, < 5.1.8 |
Weakness: CWE-407 · Vector: 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
References
- https://github.com/immutable-js/immutable-js/security/advisories/GHSA-xvcm-6775-5m9r x_refsource_CONFIRM
- https://github.com/immutable-js/immutable-js/commit/3dd7e5655012597a41873e328bf9142a8901527b x_refsource_MISC
- https://github.com/immutable-js/immutable-js/commit/e51d49fc612ded5ec4dfb94ff294d22074269b0f x_refsource_MISC
- https://github.com/immutable-js/immutable-js/releases/tag/v4.3.9 x_refsource_MISC
- https://github.com/immutable-js/immutable-js/releases/tag/v5.1.8 x_refsource_MISC