In Avast Antivirus before v17, an unprivileged user (and thus malware or a virus) can mark an arbitrary process as Trusted from the perspective of the Avast product. This bypasses the Self-Defense feature of the product, opening a door to subsequent attack on many of its components.

In Avast Antivirus before v17, using the LPC interface API exposed by the AvastSVC.exe Windows service, it is possible to launch predefined binaries, or replace or delete arbitrary files. This vulnerability is exploitable by any unprivileged user when Avast Self-Defense is disabled. It is also exploitable in conjunction with CVE-2017-8308 when Avast Self-Defense is enabled. The vulnerability allows for Denial of Service attacks and hiding traces of a possible attack.