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CVE-2026-59880

Immutable-js Immutable vulnerability

7.5 HIGHPublic exploitEPSS 0.66%
  1. Published8 Jul 2026

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 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

Immutable-js Immutable≥ 5.0.0 < 5.1.8 · < 4.3.9

Remediation

Fixed in
Immutable-js Immutable≥ 5.1.8

References

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Frequently asked

Is CVE-2026-59880 being actively exploited?

CVE-2026-59880 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.66%.

How severe is CVE-2026-59880?

CVE-2026-59880 has a CVSS 3.1 base score of 7.5, rated high. EPSS estimates a 0.66% probability of exploitation.

Which products are affected by CVE-2026-59880?

Affected products include Immutable-js Immutable.

How do I fix CVE-2026-59880?

Upgrade affected software to a fixed version, for example Immutable-js Immutable 5.1.8 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-59880 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.