If a user was convinced to drag and drop an image to their desktop or other folder, the resulting object could have been changed into an executable script which would have run arbitrary code after the user clicked on it. This vulnerability affects Firefox < 97, Thunderbird < 91.6, and Firefox ESR < 91.6.

If a user installed an extension of a particular type, the extension could have auto-updated itself and while doing so, bypass the prompt which grants the new version the new requested permissions. This vulnerability affects Firefox < 97, Thunderbird < 91.6, and Firefox ESR < 91.6.

A Time-of-Check Time-of-Use bug existed in the Maintenance (Updater) Service that could be abused to grant Users write access to an arbitrary directory. This could have been used to escalate to SYSTEM access.<br>*This bug only affects Firefox on Windows. Other operating systems are unaffected.*. This vulnerability affects Firefox < 97, Thunderbird < 91.6, and Firefox ESR < 91.6.

Mozilla developers Calixte Denizet, Kershaw Chang, Christian Holler, Jason Kratzer, Gabriele Svelto, Tyson Smith, Simon Giesecke, and Steve Fink reported memory safety bugs present in Firefox 95 and Firefox ESR 91.4. 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 ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

Malicious websites could have confused Firefox into showing the wrong origin when asking to launch a program and handling an external URL protocol. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

After accepting an untrusted certificate, handling an empty pkcs7 sequence as part of the certificate data could have lead to a crash. This crash is believed to be unexploitable. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

A race condition could have allowed bypassing the fullscreen notification which could have lead to a fullscreen window spoof being unnoticed.<br>*This bug only affects Firefox for Windows. Other operating systems are unaffected.*. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

Securitypolicyviolation events could have leaked cross-origin information for frame-ancestors violations. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

The constructed curl command from the "Copy as curl" feature in DevTools was not properly escaped for PowerShell. This could have lead to command injection if pasted into a Powershell prompt.<br>*This bug only affects Thunderbird for Windows. Other operating systems are unaffected.*. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

When navigating from inside an iframe while requesting fullscreen access, an attacker-controlled tab could have made the browser unable to leave fullscreen mode. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

When inserting text while in edit mode, some characters might have lead to out-of-bounds memory access causing a potentially exploitable crash. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

When resizing a popup while requesting fullscreen access, the popup would have become unable to leave fullscreen mode. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

Certain network request objects were freed too early when releasing a network request handle. This could have lead to a use-after-free causing a potentially exploitable crash. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

Malicious websites could have tricked users into accepting launching a program to handle an external URL protocol. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

Applying a CSS filter effect could have accessed out of bounds memory. This could have lead to a heap-buffer-overflow causing a potentially exploitable crash. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

Constructing audio sinks could have lead to a race condition when playing audio files and closing windows. This could have lead to a use-after-free causing a potentially exploitable crash. This vulnerability affects Firefox ESR < 91.5, Firefox < 96, and Thunderbird < 91.5.

When displaying the sender of an email, and the sender name contained the Braille Pattern Blank space character multiple times, Thunderbird would have displayed all the spaces. This could have been used by an attacker to send an email message with the attacker's digital signature, that was shown with an arbitrary sender email address chosen by the attacker. If the sender name started with a false email address, followed by many Braille space characters, the attacker's email address was not visible. Because Thunderbird compared the invisible sender address with the signature's email address, if the signing key or certificate was accepted by Thunderbird, the email was shown as having a valid digital signature. This vulnerability affects Thunderbird < 91.10.

If an attacker was able to corrupt the methods of an Array object in JavaScript via prototype pollution, they could have achieved execution of attacker-controlled JavaScript code in a privileged context. This vulnerability affects Firefox ESR < 91.9.1, Firefox < 100.0.2, Firefox for Android < 100.3.0, and Thunderbird < 91.9.1.

An attacker could have sent a message to the parent process where the contents were used to double-index into a JavaScript object, leading to prototype pollution and ultimately attacker-controlled JavaScript executing in the privileged parent process. This vulnerability affects Firefox ESR < 91.9.1, Firefox < 100.0.2, Firefox for Android < 100.3.0, and Thunderbird < 91.9.1.

When viewing an email message A, which contains an attached message B, where B is encrypted or digitally signed or both, Thunderbird may show an incorrect encryption or signature status. After opening and viewing the attached message B, when returning to the display of message A, the message A might be shown with the security status of message B. This vulnerability affects Thunderbird < 91.9.