CVE-2026-29063

A flaw was found in Immutable.js, a library for persistent immutable data structures. This vulnerability, known as Prototype Pollution, allows an attacker with low privileges to inject unwanted properties into core JavaScript object prototypes without user interaction. By manipulating specific APIs such as mergeDeep(), mergeDeepWith(), merge(), Map.toJS(), and Map.toObject(), a remote attacker could potentially execute arbitrary code or cause a denial of service (DoS).

Exploitation of this vulnerability requires that an attacker is able to provide arbitrary data to clients of this library in a way that calls the affected functions with data the attacker controls. In most deployments, the ability to provide data in this fashion requires that an attacker has some degree of privileges to access the affected applications.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.