Upgrade to version 4.7.844 or higher, as it has been reported to fix this vulnerability. An upgrade is required as there are no known workarounds.
Vendor Specific News/Changelog Entry: http://www.avast.com/eng/av4_revision_history.html
Secunia Advisory ID:20387
FrSIRT Advisory: ADV-2006-2115
Bugtraq ID: 18238