Cisco Secure Web Appliance Content Encoding Filter Bypass Vulnerabilities

Multiple vulnerabilities in the scanning engines of Cisco AsyncOS Software for Cisco Secure Web Appliance, formerly Cisco Web Security Appliance (WSA), could allow an unauthenticated, remote attacker to bypass a configured rule, thereby allowing traffic onto a network that should have been blocked.

These vulnerabilities exist because malformed, encoded traffic is not properly detected. An attacker could exploit these vulnerabilities by connecting through an affected device to a malicious server and receiving malformed HTTP responses. A successful exploit could allow the attacker to bypass an explicit block rule and receive traffic that should have been rejected by the device.

Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.

This advisory is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-wsa-bypass-bwBfugek [“https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-wsa-bypass-bwBfugek”]

Attention: Simplifying the Cisco portfolio includes the renaming of security products under one brand: Cisco Secure. For more information, see Meet Cisco Secure [“https://www.cisco.com/c/en/us/products/security/secure-names.html”].