Untrusted search path vulnerability in avast! Free Antivirus version 5.0.594 and earlier allows local users, and possibly remote attackers, to execute arbitrary code and conduct DLL hijacking attacks via a Trojan horse mfc90loc.dll that is located in the same folder as an avast license (.avastlic) file.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A7193