Scanning certain QR codes that included text with a website URL could allow the URL to be opened without presenting the user with a confirmation alert first This vulnerability affects Firefox for iOS < 136.

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.

It was possible to cause the browser to enter fullscreen mode without displaying the security UI; thus making it possible to attempt a phishing attack or otherwise confuse the user. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

Under certain conditions, Firefox did not display a warning when a user attempted to navigate to a new protocol handler. This vulnerability affects Firefox < 121.

When scanning QR codes, Firefox for Android would have allowed navigation to some URLs that do not point to web content.<br>*This bug only affects Firefox for Android. Other operating systems are unaffected.*. This vulnerability affects Firefox < 96.

Opening Javascript links in a new tab via long-press in the Firefox iOS client could result in a malicious script spoofing the URL of the new tab. This vulnerability affects Firefox for iOS < 134.

Firefox did not reset the address bar after the beforeunload dialog was shown if the user chose to remain on the page. This could have resulted in an incorrect URL being shown when used in conjunction with other unexpected browser behaviors. This vulnerability affects Firefox < 80.

A unicode RTL order character in the downloaded file name can be used to change the file's name during the download UI flow to change the file extension. This vulnerability affects Firefox for iOS < 28.

The z-order of the browser windows could be manipulated to hide the fullscreen notification. This could potentially be leveraged to perform a spoofing attack. This vulnerability affects Firefox < 135 and Thunderbird < 135.

Multiple prompts and panels from both Firefox and the Android OS could be used to obscure the notification announcing the transition to fullscreen mode after the fix for CVE-2023-6870 in Firefox 121. This could lead to spoofing the browser UI if the sudden appearance of the prompt distracted the user from noticing the visual transition happening behind the prompt. These notifications now use the Android Toast feature. *This bug only affects Firefox on Android. Other operating systems are unaffected.* This vulnerability affects Firefox < 130.

In multiple cases browser prompts could have been obscured by popups controlled by content. These could have led to potential user confusion and spoofing attacks. This vulnerability affects Firefox < 113, Firefox ESR < 102.11, and Thunderbird < 102.11.

When parsing internationalized domain names, high bits of the characters in the URLs were sometimes stripped, resulting in inconsistencies that could lead to user confusion or attacks such as phishing. This vulnerability affects Firefox < 94.

If a domain name contained a RTL character, it would cause the domain to be rendered to the right of the path. This could lead to user confusion and spoofing attacks. <br>*This bug only affects Firefox for Android. Other operating systems are unaffected.*<br>*Note*: Due to a clerical error this advisory was not included in the original announcement, and was added in Feburary 2022. This vulnerability affects Firefox < 92.

Due to an unusual sequence of attacker-controlled events, a Javascript alert() dialog with arbitrary (although unstyled) contents could be displayed over top an uncontrolled webpage of the attacker's choosing. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.

By displaying a form validity message in the correct location at the same time as a permission prompt (such as for geolocation), the validity message could have obscured the prompt, resulting in the user potentially being tricked into granting the permission. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.

When styling and rendering an oversized `<select>` element, Firefox did not apply correct clipping which allowed an attacker to paint over the user interface. This vulnerability affects Firefox < 89.

Thunderbird did not check if the user ID associated with an OpenPGP key has a valid self signature. An attacker may create a crafted version of an OpenPGP key, by either replacing the original user ID, or by adding another user ID. If Thunderbird imports and accepts the crafted key, the Thunderbird user may falsely conclude that the false user ID belongs to the correspondent. This vulnerability affects Thunderbird < 78.9.1.

A compromised content process could have performed session history manipulations it should not have been able to due to testing infrastructure that was not restricted to testing-only configurations. This vulnerability affects Firefox < 88.

By downloading a file with the .fileloc extension, a semi-privileged extension could launch an arbitrary application on the user's computer. The attacker is restricted as they are unable to download non-quarantined files or supply command line arguments to the application, limiting the impact. Note: this issue only occurs on Mac OSX. Other operating systems are unaffected. This vulnerability affects Thunderbird < 68.5, Firefox < 73, and Firefox < ESR68.5.