A use‑after‑free condition in the Widget component of Mozilla Firefox allows a malicious page or resource to read or otherwise manipulate memory after the object has been freed. This flaw enables an attacker to bypass the browser’s sandbox, leading to arbitrary code execution on the host system, where the attacker could gain full system privileges. The weakness is a classic example of a memory corruption vulnerability with severe confidentiality, integrity, and availability consequences.

Mozilla Firefox versions before 159 and before the ESR 153.6 release are affected. Versions 159 and newer, and ESR 153.6 and newer, contain the fix and are no longer vulnerable.

The entry contains no EPSS score and is not listed in the KEV catalog, so the exploitation probability is unknown but the flaw is of high severity. Based on the nature of the vulnerability, the attack vector is most likely remote, occurring when a user visits an attacker‑controlled website or is tricked into loading malicious content that exploits the Widget component. The lack of a publicly available EPSS score does not diminish the importance of applying the fix promptly.