If an out-of-memory condition occurs at a specific point using allocations in the probabilistic heap checker, an assertion could have been triggered, and in rarer situations, memory corruption could have occurred. This vulnerability affects Firefox < 127.

An attacker could have caused a use-after-free in the JavaScript engine to read memory in the JavaScript string section of the heap. This vulnerability affects Firefox < 127.

Offscreen Canvas did not properly track cross-origin tainting, which could be used to access image data from another site in violation of same-origin policy. This vulnerability affects Firefox < 127, Firefox ESR < 115.12, and Thunderbird < 115.12.

On Windows 10, when using the 'Save As' functionality, an attacker could have tricked the browser into saving the file with a disallowed extension such as `.url` by including an invalid character in the extension. *Note:* This issue only affected Windows operating systems. Other operating systems are unaffected. This vulnerability affects Firefox < 127, Firefox ESR < 115.12, and Thunderbird < 115.12.

By tricking the browser with a `X-Frame-Options` header, a sandboxed iframe could have presented a button that, if clicked by a user, would bypass restrictions to open a new window. This vulnerability affects Firefox < 127, Firefox ESR < 115.12, and Thunderbird < 115.12.

By monitoring the time certain operations take, an attacker could have guessed which external protocol handlers were functional on a user's system. This vulnerability affects Firefox < 127, Firefox ESR < 115.12, and Thunderbird < 115.12.

In addition to detecting when a user was taking a screenshot (XXX), a website was able to overlay the 'My Shots' button that appeared, and direct the user to a replica Firefox Screenshots page that could be used for phishing. This vulnerability affects Firefox < 127.

If a garbage collection was triggered at the right time, a use-after-free could have occurred during object transplant. This vulnerability affects Firefox < 127, Firefox ESR < 115.12, and Thunderbird < 115.12.

If a specific sequence of actions is performed when opening a new tab, the triggering principal associated with the new tab may have been incorrect. The triggering principal is used to calculate many values, including the `Referer` and `Sec-*` headers, meaning there is the potential for incorrect security checks within the browser in addition to incorrect or misleading information sent to remote websites. *This bug only affects Firefox for Android. Other versions of Firefox are unaffected.* This vulnerability affects Firefox < 127.

Memory safety bugs present in Firefox 125. 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 < 126.