Mozilla Firefox IonMonkey Switch Statement Optimization Type Confusion Remote Code Execution Vulnerability (CVE-2026-4698)

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Mozilla Firefox.

User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.

The specific flaw exists within IonMonkey when optimizing JavaScript switch statements.

The issue results from the lack of proper validation of user-supplied data, which can result in a type confusion condition.

An attacker can leverage this vulnerability to execute code in the context of the current process.

I am one of the editors here at www.systemtek.co.uk I am a UK based technology professional, with an interest in computer security and telecoms.