A vulnerability in the zip decompression engine of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass content filters that are configured on an affected device. The vulnerability is due to improper handling of password-protected zip files. An attacker could exploit this vulnerability by sending a malicious file inside a crafted zip-compressed file to an affected device. A successful exploit could allow the attacker to bypass configured content filters that would normally drop the email.
Cisco Email Security Appliance Zip Content Filter Bypass Vulnerability