Clam AntiVirus is "a multi-platform GPL anti-virus toolkit. ClamAV is often integrated into e-mail gateways and used to scan e-mail traffic for viruses. It supports virus scanning for a wide variety of packed Portable Executable (PE) binaries". Remote exploitation of an integer overflow vulnerability in Clam AntiVirus' ClamAV, as included in various vendors' operating system distributions, allows attackers to execute arbitrary code with the privileges of the affected process.

http://www.securiteam.com/securitynews/5IP0B0UNFO.html