Security Vulnerabilities fixed in Firefox ESR 78.9 — 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.
An out of date graphics library (Angle) likely contained vulnerabilities that could potentially be exploited.
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.
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.
Mozilla developers and community members Alexis Beingessner, Tyson Smith, Julien Wajsberg, and Matthew Gregan 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.