Integer overflow in Immutable-Js Immutable
CVE-2026-59879
Immutable.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 functional set, setIn, and updateIn mishandle an index or size in the range 2 ** 30 to 2 ** 31 in setListBounds in src/List.js, causing an empty List to enter an uncatchable infinite loop, a populated List to allocate without bound until process abort, or setSize to silently wrap large values. This issue is fixed in versions 4.3.9 and 5.1.8.
Vulnerability class: Integer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.007 (50.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 50.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000
Affected products
- Immutable-Js Immutable
- Immutable-Js — versions >= 5.0.0-beta.1, < 5.1.8, < 4.3.9
Weakness classification (CWE)
References
- github.com/immutable-js/immutable-js/security/advisories/GHSA-v56q-mh7h-f735 (Exploit, Mitigation, Vendor Advisory)
- github.com/immutable-js/immutable-js/commit/a1a1ee412dcaa380ab325196283d06594ff… (Patch)
- github.com/immutable-js/immutable-js/commit/f0bc997d8eb9886aff2236635aa210a95a0… (Patch)
- github.com/immutable-js/immutable-js/releases/tag/v4.3.9 (Product, Release Notes)
- github.com/immutable-js/immutable-js/releases/tag/v5.1.8 (Product, Release Notes)
Frequently asked questions
- What is CVE-2026-59879?
- CVE-2026-59879 is a high-severity vulnerability in Immutable-Js Immutable, classified under Integer Overflow or Wraparound. CVSS score: 7.5/10. Published 2026-07-08.
- How severe is CVE-2026-59879?
- High severity. CVSS v3 base score is 7.5 out of 10.