Related Vulnerabilities: CVE-2021-23999  

A security issue has been found in Firefox before version 88 and Thunderbird before version 78.10. If a Blob URL was loaded through some unusual user interaction, it could have been loaded by the System Principal and granted additional privileges that should not be granted to web content.

Severity Medium

Remote Yes

Type Sandbox escape

Description

A security issue has been found in Firefox before version 88 and Thunderbird before version 78.10. If a Blob URL was loaded through some unusual user interaction, it could have been loaded by the System Principal and granted additional privileges that should not be granted to web content.

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-2021-23999
https://www.mozilla.org/en-US/security/advisories/mfsa2021-14/#CVE-2021-23999
https://bugzilla.mozilla.org/show_bug.cgi?id=1691153