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.
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Exploitation outlook
- Low exploitation risk0.37% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 29% of all EPSS-scored CVEs.
Advisory coverage (1)
External references
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[](https://www.csirts.com/cve/CVE-2026-59879)