Cisco Web Security appliance was found to be prone to remote denial of service vulnerability. This vulnerability could be exploited to cause unexpected restart of proxy process. This in-turn would deny service to legitimate users. The vulnerabilities were found in Cisco Web Security Appliance 11.7.0-FCS-334, Cisco Web Security Appliance 10.5.2-072, Cisco Cisco Web Security Appliance 10.5.3-025, Cisco AsyncOS Software 11.5, Cisco AsyncOS Software 10.5 Cisco AsyncOS Software 10.1, Cisco AsyncOS Software 10.0.