Critical severity · published Mar 6, 2026
CVE-2026-29063
Immutable.js: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in immutable
9.8
CVSS
1%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.0% · higher than 63% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
IM
immutable-js · immutable-js
< 3.8.3; < 4.3.7; < 5.1.5 · source: vendor
IM
Immutable · Immutable-js
3.0.0 before 3.8.3; 4.0.0 before 4.3.7; 5.0.0 before 5.1.5 · source: NVD
CO
Cluster Observability Operator 1.5.0 · Red Hat
All versions, or not specified · source: CISA
LS
Logging Subsystem for Red Hat OpenShift · Red Hat
All versions, or not specified · source: CISA
MT
Migration Toolkit for Virtualization 2.1 · Red Hat
All versions, or not specified · source: CISA
MT
Migration Toolkit for Virtualization 2.9 · Red Hat
All versions, or not specified · source: CISA
NO
Network Observability (NETOBSERV) 1.11.0 · Red Hat
All versions, or not specified · source: CISA
NO
Network Observability (NETOBSERV) 1.12.2 · Red Hat
All versions, or not specified · source: CISA
NH
Node HealthCheck Operator · Red Hat
All versions, or not specified · source: CISA
OL
OpenShift Lightspeed · Red Hat
All versions, or not specified · source: CISA
OP
OpenShift Pipelines · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat 3scale API Management Platform 2 · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-29063
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-29063
Release Notes
https://github.com/immutable-js/immutable-js/releases/tag/v3.8.3
Release Notes
https://github.com/immutable-js/immutable-js/releases/tag/v4.3.8
Release Notes
https://github.com/immutable-js/immutable-js/releases/tag/v5.1.5
Exploit
https://github.com/immutable-js/immutable-js/security/advisories/GHSA-wf6x-7x77-mvgw
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:11070
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:11217
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