Mozilla Firefox 80, Mozilla Firefox ESR 68.12, Mozilla Firefox ESR 78.2, Mozilla Thunderbird 68.12 and Mozilla Thunderbird 78.2 : If Firefox is installed to a user-writable directory, the Mozilla Maintenance Service would execute updater.exe from the install location with administrative privileges. Although the Mozilla Maintenance Service does ensure that updater.exe is signed by Mozilla, the version could have been rolled back to a previous version which would have allowed exploitation of an older bug and arbitrary code execution with system privileges.