Security Vulnerabilities fixed in Firefox ESR 91.4.0 — Mozilla

Under certain circumstances, asynchronous functions could have caused a navigation to fail but expose the target URL.
An incorrect type conversion of sizes from 64bit to 32bit integers allowed an attacker to corrupt memory leading to a potentially exploitable crash.
By misusing a race in our notification code, an attacker could have forcefully hidden the notification for pages that had received full screen and pointer lock access, which could have been used for spoofing attacks.
Failure to correctly record the location of live pointers across wasm instance calls resulted in a GC occurring within the call not tracing those live pointers. This could have led to a use-after-free causing a potentially exploitable crash.
When invoking protocol handlers for external protocols, a supplied parameter URL containing spaces was not properly escaped.
Using XMLHttpRequest, an attacker could have identified installed applications by probing error messages for loading external protocols.
Documents loaded with the CSP sandbox directive could have escaped the sandbox’s script restriction by embedding additional content.
Using the Location API in a loop could have caused severe application hangs and crashes.
It was possible to recreate previous cursor spoofing attacks against users with a zoomed native cursor.
Mozilla developers and community members Julian Hector, Randell Jesup, Gabriele Svelto, Tyson Smith, Christian Holler, and Masayuki Nakano reported memory safety bugs present in Firefox 94 and Firefox ESR 91.3. 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.