Firefox's HTML parser did not correctly interpret HTML comment tags, resulting in an incongruity with other browsers. This could have been used to escape HTML comments on pages that put user-controlled data in them. This vulnerability affects Firefox < 101.
An attacker could have exploited a timing attack by sending a large number of allowCredential entries and detecting the difference between invalid key handles and cross-origin key handles. This could have led to cross-origin account linking in violation of WebAuthn goals. This vulnerability affects Thunderbird < 91.10, Firefox < 101, and Firefox ESR < 91.10.
A crafted CMS message could have been processed incorrectly, leading to an invalid memory read, and potentially further memory corruption. This vulnerability affects Thunderbird < 91.10, Firefox < 101, and Firefox ESR < 91.10.
On arm64, WASM code could have resulted in incorrect assembly generation leading to a register allocation problem, and a potentially exploitable crash. This vulnerability affects Thunderbird < 91.10, Firefox < 101, and Firefox ESR < 91.10.
When exiting fullscreen mode, an iframe could have confused the browser about the current state of fullscreen, resulting in potential user confusion or spoofing attacks. This vulnerability affects Thunderbird < 91.10, Firefox < 101, and Firefox ESR < 91.10.
A malicious webpage could have caused an out-of-bounds write in WebGL, leading to memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 91.10, Firefox < 101, and Firefox ESR < 91.10.
A malicious website could have learned the size of a cross-origin resource that supported Range requests. This vulnerability affects Thunderbird < 91.10, Firefox < 101, and Firefox ESR < 91.10.
Mozilla developers Gabriele Svelto, Randell Jesup and the Mozilla Fuzzing Team reported memory safety bugs present in Firefox 99. 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 < 100.
Mozilla developers Andrew McCreight, Gabriele Svelto, Tom Ritter and the Mozilla Fuzzing Team reported memory safety bugs present in Firefox 99 and Firefox ESR 91.8. 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 < 91.9, Firefox ESR < 91.9, and Firefox < 100.
Firefox behaved slightly differently for already known resources when loading CSS resources involving CSS variables. This could have been used to probe the browser history. This vulnerability affects Thunderbird < 91.9, Firefox ESR < 91.9, and Firefox < 100.
The Performance API did not properly hide the fact whether a request cross-origin resource has observed redirects. This vulnerability affects Firefox < 100.
When reusing existing popups Firefox would have allowed them to cover the fullscreen notification UI, which could have enabled browser spoofing attacks. This vulnerability affects Thunderbird < 91.9, Firefox ESR < 91.9, and Firefox < 100.
Requests initiated through reader mode did not properly omit cookies with a SameSite attribute. This vulnerability affects Thunderbird < 91.9, Firefox ESR < 91.9, and Firefox < 100.
An improper implementation of the new iframe sandbox keyword <code>allow-top-navigation-by-user-activation</code> could lead to script execution without <code>allow-scripts</code> being present. This vulnerability affects Thunderbird < 91.9, Firefox ESR < 91.9, and Firefox < 100.
Documents in deeply-nested cross-origin browsing contexts could have obtained permissions granted to the top-level origin, bypassing the existing prompt and wrongfully inheriting the top-level permissions. This vulnerability affects Thunderbird < 91.9, Firefox ESR < 91.9, and Firefox < 100.
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.
Mozilla developers and community members Randell Jesup, Sebastian Hengst, and the Mozilla Fuzzing Team reported memory safety bugs present in Firefox 98. 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 < 99.
In unusual circumstances, selecting text could cause text selection caching to behave incorrectly, leading to a crash. This vulnerability affects Firefox < 99.
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.