Memory safety bugs present in Firefox 132, Firefox ESR 128.4, and Thunderbird 128.4. 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 < 133, Firefox ESR < 128.5, Thunderbird < 133, and Thunderbird < 128.5.

A flaw in handling fullscreen transitions may have inadvertently caused the application to become stuck in fullscreen mode when a modal dialog was opened during the transition. This issue left users unable to exit fullscreen mode using standard actions like pressing "Esc" or accessing right-click menus, resulting in a disrupted browsing experience until the browser is restarted. *This bug only affects the application when running on macOS. Other operating systems are unaffected.* This vulnerability affects Firefox < 133, Firefox ESR < 128.5, Thunderbird < 133, and Thunderbird < 128.5.

When handling keypress events, an attacker may have been able to trick a user into bypassing the "Open Executable File?" confirmation dialog. This could have led to malicious code execution. This vulnerability affects Firefox < 133, Firefox ESR < 128.5, Thunderbird < 133, and Thunderbird < 128.5.

The application failed to account for exceptions thrown by the `loadManifestFromFile` method during add-on signature verification. This flaw, triggered by an invalid or unsupported extension manifest, could have caused runtime errors that disrupted the signature validation process. As a result, the enforcement of signature validation for unrelated add-ons may have been bypassed. Signature validation in this context is used to ensure that third-party applications on the user's computer have not tampered with the user's extensions, limiting the impact of this issue. This vulnerability affects Firefox < 133, Firefox ESR < 128.5, Thunderbird < 133, and Thunderbird < 128.5.

A crafted URL containing Arabic script and whitespace characters could have hidden the true origin of the page, resulting in a potential spoofing attack. This vulnerability affects Firefox < 133, Firefox ESR < 128.5, Thunderbird < 133, and Thunderbird < 128.5.

Enhanced Tracking Protection's Strict mode may have inadvertently allowed a CSP `frame-src` bypass and DOM-based XSS through the Google SafeFrame shim in the Web Compatibility extension. This issue could have exposed users to malicious frames masquerading as legitimate content. This vulnerability affects Firefox < 133, Firefox ESR < 128.5, Firefox ESR < 115.18, Thunderbird < 133, Thunderbird < 128.5, and Thunderbird < 115.18.

The executable file warning was not presented when downloading .library-ms files. *Note: This issue only affected Windows operating systems. Other operating systems are unaffected.* This vulnerability affects Firefox < 133, Firefox ESR < 128.5, Thunderbird < 133, and Thunderbird < 128.5.

An attacker could cause a select dropdown to be shown over another tab; this could have led to user confusion and possible spoofing attacks. This vulnerability affects Firefox < 133, Firefox ESR < 128.5, Thunderbird < 133, and Thunderbird < 128.5.

Certain WebGL operations on Apple silicon M series devices could have lead to an out-of-bounds write and memory corruption due to a flaw in Apple's GPU driver. *This bug only affected the application on Apple M series hardware. Other platforms were unaffected.* This vulnerability affects Firefox < 133, Firefox ESR < 128.5, Firefox ESR < 115.18, Thunderbird < 133, Thunderbird < 128.5, and Thunderbird < 115.18.

A malicious website could have included an iframe with an malformed URI resulting in a non-exploitable browser crash. This vulnerability affects Firefox < 126.

Memory safety bugs present in Firefox 131, Firefox ESR 128.3, and Thunderbird 128.3. 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 < 132, Firefox ESR < 128.4, Thunderbird < 128.4, and Thunderbird < 132.

By sending a specially crafted push message, a remote server could have hung the parent process, causing the browser to become unresponsive. This vulnerability affects Firefox < 132, Firefox ESR < 128.4, Thunderbird < 128.4, and Thunderbird < 132.

A clipboard "paste" button could persist across tabs which allowed a spoofing attack. This vulnerability affects Firefox < 132, Firefox ESR < 128.4, Thunderbird < 128.4, and Thunderbird < 132.

Repeated writes to history interface attributes could have been used to cause a Denial of Service condition in the browser. This was addressed by introducing rate-limiting to this API. This vulnerability affects Firefox < 132, Firefox ESR < 128.4, Thunderbird < 128.4, and Thunderbird < 132.

Video frames could have been leaked between origins in some situations. This vulnerability affects Firefox < 132, Firefox ESR < 128.4, Firefox ESR < 115.17, Thunderbird < 128.4, and Thunderbird < 132.

Truncation of a long URL could have allowed origin spoofing in a permission prompt. This vulnerability affects Firefox < 132, Firefox ESR < 128.4, Thunderbird < 128.4, and Thunderbird < 132.

In multipart/x-mixed-replace responses, `Content-Disposition: attachment` in the response header was not respected and did not force a download, which could allow XSS attacks. This vulnerability affects Firefox < 132, Firefox ESR < 128.4, Thunderbird < 128.4, and Thunderbird < 132.

The origin of an external protocol handler prompt could have been obscured using a data: URL within an `iframe`. This vulnerability affects Firefox < 132, Firefox ESR < 128.4, Thunderbird < 128.4, and Thunderbird < 132.

An attacker could have caused a use-after-free when accessibility was enabled, leading to a potentially exploitable crash. This vulnerability affects Firefox < 132, Firefox ESR < 128.4, Firefox ESR < 115.17, Thunderbird < 128.4, and Thunderbird < 132.

A permission leak could have occurred from a trusted site to an untrusted site via `embed` or `object` elements. This vulnerability affects Firefox < 132, Firefox ESR < 128.4, Firefox ESR < 115.17, Thunderbird < 128.4, and Thunderbird < 132.