Vulnerability Instance

Security researcher Frédéric Hoguin reported a mechanism where the
Mozilla Windows updater could be used to overwrite arbitrary files. He found that files
extracted by the updater from a MAR archive are not locked for writing and
can be overwritten by other processes while the updater is running. A malicious local
program could invoke the updater and then interfere with the extracted files, replacing
them with its own. This vulnerability could be used for privilege escalation if these
overwritten files were later invoked by other Windows components that had higher
privileges. 
This issue does not affect non-Windows operating systems.