avast! Server Edition before 4.7.726 does not demand a password in a certain intended context, even when a password has been set, which allows local users to bypass authentication requirements.

Heap-based buffer overflow in alwil avast! Anti-virus Engine before 4.7.869 allows remote attackers to execute arbitrary code via a crafted LHA file that contains extended headers with file and directory names whose concatenation triggers the overflow.

Unspecified vulnerability in the CHM unpacker in avast! before 4.7.844 has unknown impact and remote attack vectors.

avast! 4 Linux Home Edition 1.0.5 allows local users to modify permissions of arbitrary files via a symlink attack on the /tmp/_avast4_ temporary directory.

avast! Antivirus 4.6.763 and earlier sets "BUILTIN\Everyone" permissions to critical system files in the installation folder, which allows local users to gain privileges or disable protection by modifying those files.

Multiple interpretation error in unspecified versions of Avast Antivirus allows remote attackers to bypass virus detection via a malicious executable in a specially crafted RAR file with malformed central and local headers, which can still be opened by products such as Winrar and PowerZip, even though they are rejected as corrupted by Winzip and BitZipper.

Buffer overflow in a third-party compression library (UNACEV2.DLL), as used in avast! Antivirus Home/Professional Edition 4.6.665 and Server Edition 4.6.460, allows remote attackers to execute arbitrary code via an ACE archive containing a long filename.

Directory traversal vulnerability in a third-party compression library (UNACEV2.DLL), as used in avast! Antivirus Home/Professional Edition 4.6.665 and Server Edition 4.6.460, allows remote attackers to write arbitrary files via an ACE archive containing filenames with (1) .. or (2) absolute pathnames.

Buffer overflow in the Aavmker4 device driver in Avast! Antivirus 4.6 and possibly other versions allows local users to cause a denial of service (system crash) and possibly execute arbitrary code via certain signals combined with crafted input.

Unknown vulnerability in ALWIL avast! antivirus 4 (4.6.6230) and earlier, when running on Windows NT 4.0, does not properly detect certain viruses.