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CVE-2026-29063

Immutable-js Immutable vulnerability

9.8 CRITICALPublic exploitEPSS 1.61%
  1. Published6 Mar 2026

Description

Immutable.js provides many Persistent Immutable data structures. Prior to versions 3.8.3, 4.3.7, and 5.1.5, Prototype Pollution is possible in immutable via the mergeDeep(), mergeDeepWith(), merge(), Map.toJS(), and Map.toObject() APIs. This issue has been patched in versions 3.8.3, 4.3.7, and 5.1.5.

CVSS 3.1 breakdown

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

Affected products

Immutable-js Immutable≥ 3.0.0 < 3.8.3 · ≥ 4.0.0 < 4.3.7 · ≥ 5.0.0 < 5.1.5

Remediation

Fixed in
Immutable-js Immutable≥ 3.8.3

References

and 62 more references

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Frequently asked

Is CVE-2026-29063 being actively exploited?

CVE-2026-29063 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 1.61%.

How severe is CVE-2026-29063?

CVE-2026-29063 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 1.61% probability of exploitation.

Which products are affected by CVE-2026-29063?

Affected products include Immutable-js Immutable.

How do I fix CVE-2026-29063?

Upgrade affected software to a fixed version, for example Immutable-js Immutable 3.8.3 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-29063 against the real software inventory on every managed device, every day. 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.