Cisco Web Security Appliance Cached Range Request Denial of Service Vulnerability

A vulnerability in the cached file-range request functionality of Cisco AsyncOS for Cisco Web Security Appliance (WSA) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an appliance due to the appliance running out of system memory.

The vulnerability is due to a failure to free memory when a file range for cached content is requested through the WSA. An attacker could exploit this vulnerability by opening multiple connections that request file ranges through the affected device. A successful exploit could allow the attacker to cause the WSA to stop passing traffic when enough memory is used and not freed.

Cisco has released software updates that address this vulnerability. A workaround that addresses this vulnerability is also available.

This advisory is available at the following link:

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160518-wsa2[“https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20160518-wsa2”]