Following the recent Chrome sandbox escape (CVE-2025-2783), various Firefox developers identified a similar pattern in our IPC code. A compromised child process could cause the parent process to return an unintentionally powerful handle, leading to a sandbox escape. The original vulnerability was being exploited in the wild. This only affects Firefox on Windows. Other operating systems are unaffected.

An attacker was able to perform an out-of-bounds read or write on a JavaScript Promise object. This vulnerability was fixed in Firefox 138.0.4, Firefox ESR 128.10.1, Firefox ESR 115.23.1, Thunderbird 128.10.2, and Thunderbird 138.0.2.

An attacker was able to perform an out-of-bounds read or write on a JavaScript object by confusing array index sizes.

Chromium: CVE-2023-4863 Heap buffer overflow in WebP

Chromium: CVE-2023-5217 Heap buffer overflow in vp8 encoding in libvpx

An attacker was able to inject an event handler into a privileged object that would allow arbitrary JavaScript execution in the parent process. Note: This vulnerability affects Desktop Firefox only, it does not affect mobile versions of Firefox. This vulnerability affects Firefox < 124.0.1 and Firefox ESR < 115.9.1.