Integer overflow in Mozilla products - CVE-2026-4689

Detailed vulnerability description

The vulnerability allows a remote attacker to escape the sandbox.

The vulnerability exists due to incorrect boundary conditions, integer overflow in the XPCOM component when processing data. A remote attacker can trick the victim into visiting a specially crafted website and escape the sandbox.

Exploitation could lead to sandbox escape and arbitrary code execution in the context of the underlying operating system.

How to mitigate CVE-2026-4689

Sources

• https://www.mozilla.org/en-US/security/advisories/mfsa2026-21/
• https://www.mozilla.org/en-US/security/advisories/mfsa2026-22/
• https://www.mozilla.org/en-US/security/advisories/mfsa2026-20/
• https://bugzilla.mozilla.org/show_bug.cgi?id=2016374