Sophos virus detection engine 2.75 on Linux and Unix, as used in Sophos Email Appliance, Pure Message for Unix, and Sophos Anti-Virus Interface (SAVI), allows remote attackers to cause a denial of service (engine crash) via zero-length MIME attachments.
https://exchange.xforce.ibmcloud.com/vulnerabilities/43703
http://www.vupen.com/english/advisories/2008/2053/references
http://www.sophos.com/support/knowledgebase/article/42245.html?_log_from=rss
http://www.securitytracker.com/id?1020462