Related Vulnerabilities: CVE-2021-23995  

A security issue has been found in Firefox before version 88 and Thunderbird before version 78.10. When Responsive Design Mode was enabled, it used references to objects that were previously freed. Mozilla presumes that with enough effort this could have been exploited to run arbitrary code.

Severity High

Remote Yes

Type Arbitrary code execution

Description

A security issue has been found in Firefox before version 88 and Thunderbird before version 78.10. When Responsive Design Mode was enabled, it used references to objects that were previously freed. Mozilla presumes that with enough effort this could have been exploited to run arbitrary code.

AVG-1836 thunderbird 78.9.1-3 High Vulnerable

AVG-1834 firefox 87.0-2 88.0-1 High Testing

https://www.mozilla.org/en-US/security/advisories/mfsa2021-16/#CVE-2021-23995
https://www.mozilla.org/en-US/security/advisories/mfsa2021-14/#CVE-2021-23995
https://bugzilla.mozilla.org/show_bug.cgi?id=1699835