CVE-2026-29063

Immutable.js: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in immutable

CVSS 8.7 HIGHEPSS 0.6%CWE-1321

Vexday Risk Score

21Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 8.7EPSS 0.6%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

06 Mar 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Affected products

immutable-js · immutable-js

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References

https://github.com/immutable-js/immutable-js/releases/tag/v3.8.3 https://github.com/immutable-js/immutable-js/releases/tag/v4.3.8 https://github.com/immutable-js/immutable-js/releases/tag/v5.1.5 https://github.com/immutable-js/immutable-js/security/advisories/GHSA-wf6x-7x77-mvgw