Security Vulnerabilities fixed in Firefox 127 — Mozilla

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.*
If a garbage collection was triggered at the right time, a use-after-free could have occurred during object transplant.
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.
By monitoring the time certain operations take, an attacker could have guessed which external protocol handlers were functional on a user’s system.
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.
On Windows, 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.
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.
An attacker could have caused a use-after-free in the JavaScript engine to read memory in the JavaScript string section of the heap.
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.
By manipulating the text in an tag, an attacker could have caused corrupt memory leading to a potentially exploitable crash.
A website was able to detect when a user took a screenshot of a page using the built-in Screenshot functionality in Firefox.
By manipulating the fullscreen feature while opening a data-list, an attacker could have overlaid a text box over the address bar. This could have led to user confusion and possible spoofing attacks.
In violation of spec, cookie prefixes such as __Secure were being ignored if they were not correctly capitalized - by spec they should be checked with a case-insensitive comparison. This could have resulted in the browser not correctly honoring the behaviors specified by the prefix.
Memory safety bugs present in Firefox 126, Firefox ESR 115.11, and Thunderbird 115.11. 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.
Memory safety bugs present in Firefox 126. 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.