Memory safety bugs present in Firefox 133, Thunderbird 133, Firefox ESR 115.18, Firefox ESR 128.5, Thunderbird 115.18, and Thunderbird 128.5. 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 < 134, Firefox ESR < 128.6, Firefox ESR < 115.19, Thunderbird < 134, and Thunderbird < 128.6.

When segmenting specially crafted text, segmentation would corrupt memory leading to a potentially exploitable crash. This vulnerability affects Firefox < 134, Firefox ESR < 128.6, Thunderbird < 134, and Thunderbird < 128.6.

Parsing a JavaScript module as JSON could, under some circumstances, cause cross-compartment access, which may result in a use-after-free. This vulnerability affects Firefox < 134, Firefox ESR < 128.6, Thunderbird < 134, and Thunderbird < 128.6.

When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site. This vulnerability affects Firefox < 134, Firefox ESR < 128.6, Thunderbird < 134, and Thunderbird < 128.6.

Assuming a controlled failed memory allocation, an attacker could have caused a use-after-free, leading to a potentially exploitable crash. This vulnerability affects Firefox < 134, Firefox ESR < 128.6, Firefox ESR < 115.19, Thunderbird < 134, and Thunderbird < 128.6.

The WebChannel API, which is used to transport various information across processes, did not check the sending principal but rather accepted the principal being sent. This could have led to privilege escalation attacks. This vulnerability affects Firefox < 134, Firefox ESR < 128.6, Thunderbird < 134, and Thunderbird < 128.6.

Missing thread synchronization primitives could have led to a data race on members of the PlaybackParams structure. This vulnerability affects Firefox < 133 and Thunderbird < 133.

A null pointer dereference may have inadvertently occurred in `pk12util`, and specifically in the `SEC_ASN1DecodeItem_Util` function, when handling malformed or improperly formatted input files. This vulnerability affects Firefox < 133 and Thunderbird < 133.

`NSC_DeriveKey` inadvertently assumed that the `phKey` parameter is always non-NULL. When it was passed as NULL, a segmentation fault (SEGV) occurred, leading to crashes. This behavior conflicted with the PKCS#11 v3.0 specification, which allows `phKey` to be NULL for certain mechanisms. This vulnerability affects Firefox < 133 and Thunderbird < 133.

A double-free issue could have occurred in `sec_pkcs7_decoder_start_decrypt()` when handling an error path. Under specific conditions, the same symmetric key could have been freed twice, potentially leading to memory corruption. This vulnerability affects Firefox < 133, Thunderbird < 133, Firefox ESR < 128.7, and Thunderbird < 128.7.

On Android, Firefox may have inadvertently allowed viewing saved passwords without the required device PIN authentication. This vulnerability affects Firefox < 133.

Copying sensitive information from Private Browsing tabs on Android, such as passwords, may have inadvertently stored data in the cloud-based clipboard history if enabled. This vulnerability affects Firefox < 133 and Thunderbird < 133.

The incorrect domain may have been displayed in the address bar during an interrupted navigation attempt. This could have led to user confusion and possible spoofing attacks. This vulnerability affects Firefox < 133 and Thunderbird < 133.

Malicious websites may have been able to perform user intent confirmation through tapjacking. This could have led to users unknowingly approving the launch of external applications, potentially exposing them to underlying vulnerabilities. This vulnerability affects Firefox < 133 and Thunderbird < 133.

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.