Mozilla developers and community members Nika Layzell, Andrew McCreight, Gabriele Svelto, and the Mozilla Fuzzing Team reported memory safety bugs present in Thunderbird 91.7. 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 Thunderbird < 91.8, Firefox < 99, and Firefox ESR < 91.8.

Due to a layout change, iframe contents could have been rendered outside of its border. This could have led to user confusion or spoofing attacks. This vulnerability affects Thunderbird < 91.8, Firefox < 99, and Firefox ESR < 91.8.

When generating the assembly code for <code>MLoadTypedArrayElementHole</code>, an incorrect AliasSet was used. In conjunction with another vulnerability this could have been used for an out of bounds memory read. This vulnerability affects Thunderbird < 91.8, Firefox < 99, and Firefox ESR < 91.8.

By using a link with <code>rel="localization"</code> a use-after-free could have been triggered by destroying an object during JavaScript execution and then referencing the object through a freed pointer, leading to a potential exploitable crash. This vulnerability affects Thunderbird < 91.8, Firefox < 99, and Firefox ESR < 91.8.

If a compromised content process sent an unexpected number of WebAuthN Extensions in a Register command to the parent process, an out of bounds write would have occurred leading to memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 91.8, Firefox < 99, and Firefox ESR < 91.8.

An unexpected message in the WebGPU IPC framework could lead to a use-after-free and exploitable sandbox escape. We have had reports of attacks in the wild abusing this flaw. This vulnerability affects Firefox < 97.0.2, Firefox ESR < 91.6.1, Firefox for Android < 97.3.0, Thunderbird < 91.6.2, and Focus < 97.3.0.

Removing an XSLT parameter during processing could have lead to an exploitable use-after-free. We have had reports of attacks in the wild abusing this flaw. This vulnerability affects Firefox < 97.0.2, Firefox ESR < 91.6.1, Firefox for Android < 97.3.0, Thunderbird < 91.6.2, and Focus < 97.3.0.

When installing an add-on, Firefox verified the signature before prompting the user; but while the user was confirming the prompt, the underlying add-on file could have been modified and Firefox would not have noticed. This vulnerability affects Firefox < 98, Firefox ESR < 91.7, and Thunderbird < 91.7.

Previously Firefox for macOS and Linux would download temporary files to a user-specific directory in <code>/tmp</code>, but this behavior was changed to download them to <code>/tmp</code> where they could be affected by other local users. This behavior was reverted to the original, user-specific directory. <br>*This bug only affects Firefox for macOS and Linux. Other operating systems are unaffected.*. This vulnerability affects Firefox ESR < 91.7 and Thunderbird < 91.7.

If an attacker could control the contents of an iframe sandboxed with <code>allow-popups</code> but not <code>allow-scripts</code>, they were able to craft a link that, when clicked, would lead to JavaScript execution in violation of the sandbox. This vulnerability affects Firefox < 98, Firefox ESR < 91.7, and Thunderbird < 91.7.

When resizing a popup after requesting fullscreen access, the popup would not display the fullscreen notification. This vulnerability affects Firefox < 98, Firefox ESR < 91.7, and Thunderbird < 91.7.

An attacker could have caused a use-after-free by forcing a text reflow in an SVG object leading to a potentially exploitable crash. This vulnerability affects Firefox < 98, Firefox ESR < 91.7, and Thunderbird < 91.7.

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.

When importing a revoked key that specified key compromise as the revocation reason, Thunderbird did not update the existing copy of the key that was not yet revoked, and the existing key was kept as non-revoked. Revocation statements that used another revocation reason, or that didn't specify a revocation reason, were unaffected. This vulnerability affects Thunderbird < 91.8.

After a VR Process is destroyed, a reference to it may have been retained and used, leading to a use-after-free and potentially exploitable crash. This vulnerability affects Thunderbird < 91.8 and Firefox ESR < 91.8.

<code>NSSToken</code> objects were referenced via direct points, and could have been accessed in an unsafe way on different threads, leading to a use-after-free and potentially exploitable crash. This vulnerability affects Thunderbird < 91.8, Firefox < 99, and Firefox ESR < 91.8.

It may be possible for an attacker to craft an email message that causes Thunderbird to perform an out-of-bounds write of one byte when processing the message. This vulnerability affects Thunderbird < 91.6.1.