Clam AntiVirus is a GPL anti-virus toolkit, designed for integration with mail servers to perform attachment scanning. Clam AntiVirus also provides a command line scanner and a tool for fetching updates of the virus database.
Neel Mehta and Alex Wheeler discovered that Clam AntiVirus is vulnerable to integer overflows when handling the TNEF, CHM and FSG file formats.
By sending a specially-crafted file an attacker could execute arbitrary code with the permissions of the user running Clam AntiVirus.
There is no known workaround at this time.
All Clam AntiVirus users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=app-antivirus/clamav-0.86.2"