How severe is CVE-2026-59879?

CVE-2026-59879 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-59879 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-59879?

CVE-2026-59879 affects Immutable-js Immutable. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-59879?

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-2026-59879 published?

CVE-2026-59879 was published on 2026-07-08 and last updated on 2026-07-10.

CVE-2026-59879

CVE-2026-59879 is a high-severity vulnerability in Immutable-js Immutable with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-190.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 8.7
EPSS exploit prediction: 0% (37th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-190
Affected product: Immutable-js Immutable
Published: 2026-07-08
Last modified: 2026-07-10

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-59879?: CVE-2026-59879 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-59879 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-59879?: CVE-2026-59879 affects Immutable-js Immutable. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-59879?: 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-2026-59879 published?: CVE-2026-59879 was published on 2026-07-08 and last updated on 2026-07-10.

References

Affected products (1)

cpe:2.3:a:immutable-js:immutable:*:*:*:*:*:node.js:*:*

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