Security Vulnerabilities fixed in Firefox 87 — Mozilla

A transient execution vulnerability, named Floating Point Value Injection (FPVI) allowed an attacker to leak arbitrary memory addresses and may have also enabled JIT type confusion attacks. (A related vulnerability, Speculative Code Store Bypass (SCSB), did not affect Firefox.)
A texture upload of a Pixel Buffer Object could have confused the WebGL code to skip binding the buffer used to unpack it, resulting in memory corruption and a potentially exploitable information leak or crash.
The Mozilla Maintenance Service granted SERVICE_START access to BUILTIN|Users which, in a domain network, grants normal remote users access to start or stop the service. This could be used to prevent the browser update service from operating (if an attacker spammed the ‘Stop’ command); but also exposed attack surface in the maintenance service.Note: This issue only affected Windows operating systems older than Win 10 build 1709. Other operating systems are unaffected.
Using techniques that built on the slipstream research, a malicious webpage could have scanned both an internal network’s hosts as well as services running on the user’s local machine utilizing WebRTC connections.
By causing a transition on a parent node by removing a CSS rule, an invalid property for a marker could have been applied, resulting in memory corruption and a potentially exploitable crash.
A malicious extension could have opened a popup window lacking an address bar. The title of the popup lacking an address bar should not be fully controllable, but in this situation was. This could have been used to spoof a website and attempt to trick the user into providing credentials.
If an attacker is able to alter specific about:config values (for example malware running on the user’s computer), the Devtools remote debugging feature could have been enabled in a way that was unnoticable to the user. This would have allowed a remote attacker (able to make a direct network connection to the victim) to monitor the user’s browsing activity and (plaintext) network traffic. This was addressed by providing a visual cue when Devtools has an open network socket.
A malicious extension with the ‘search’ permission could have installed a new search engine whose favicon referenced a cross-origin URL. The response to this cross-origin request could have been read by the extension, allowing a same-origin policy bypass by the extension, which should not have cross-origin permissions. This cross-origin request was made without cookies, so the sensitive information disclosed by the violation was limited to local-network resources or resources that perform IP-based authentication.
Mozilla developers and community members Matthew Gregan, Tyson Smith, Julien Wajsberg, and Alexis Beingessner reported memory safety bugs present in Firefox 86 and Firefox ESR 78.8. 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.
Mozilla developers Tyson Smith and Christian Holler reported memory safety bugs present in Firefox 86. 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.