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CRITICAL

CVE-2026-29063

CVSS v3

9.8

CRITICAL

EPSS Score

1.2 %

exploit probability, as of 2026-09-25

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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.

Technical details

Published
2026-03-06
Last Modified
2026-04-17

Frequently asked questions

What is CVE-2026-29063?

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.

Is CVE-2026-29063 actively exploited?

Active exploitation of CVE-2026-29063 has not been confirmed. Its EPSS score was 1.2% on 2026-09-25, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-29063?

CVE-2026-29063 has a CVSS v3 base score of 9.8 (CRITICAL severity).

Is CVE-2026-29063 affecting your environment?

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