Memory safety bugs present in Firefox 125, Firefox ESR 115.10, and Thunderbird 115.10. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 126, Firefox ESR < 115.11, and Thunderbird < 115.11.

A file dialog shown while in full-screen mode could have resulted in the window remaining disabled. This vulnerability affects Firefox < 126.

An iterator stop condition was missing when handling WASM code in the built-in profiler, potentially leading to invalid memory access and undefined behavior. *Note:* This issue only affects the application when the profiler is running. This vulnerability affects Firefox < 126.

The `ShmemCharMapHashEntry()` code was susceptible to potentially undefined behavior by bypassing the move semantics for one of its data members. This vulnerability affects Firefox < 126.

When a network error occurred during page load, the prior content could have remained in view with a blank URL bar. This could have been used to obfuscate a spoofed web site. This vulnerability affects Firefox < 126.

An HTTP digest authentication nonce value was generated using `rand()` which could lead to predictable values. This vulnerability affects Firefox < 126.

A memory allocation check was missing which would lead to a use-after-free if the allocation failed. This could have triggered a crash or potentially be leveraged to achieve code execution. This vulnerability affects Firefox < 126.

When saving a page to PDF, certain font styles could have led to a potential use-after-free crash. This vulnerability affects Firefox < 126, Firefox ESR < 115.11, and Thunderbird < 115.11.

When importing resources using Web Workers, error messages would distinguish the difference between `application/javascript` responses and non-script responses. This could have been abused to learn information cross-origin. This vulnerability affects Firefox < 126, Firefox ESR < 115.11, and Thunderbird < 115.11.

A bug in popup notifications' interaction with WebAuthn made it easier for an attacker to trick a user into granting permissions. This vulnerability affects Firefox < 126, Firefox ESR < 115.11, and Thunderbird < 115.11.