Symptom:
A vulnerability in URL filtering of Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass URL filtering on an affected device.

The vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by sending a crafted, malicious HTTP request to an affected device. A successful exploit could allow the attacker to redirect users to malicious sites.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ESA-filt-39jXvMfM

Conditions:
At the time of publication, this vulnerability affected Cisco ESA software releases earlier than Release 13.0.1 and Release 13.5.1.
At the time of publication, Cisco ESA software releases 13.0.1 and later and releases 13.5.1 and later contained the fix for this vulnerability.