Cisco Secure Web Appliance Content Encoding Filter Bypass Vulnerabilities
Update for March 2, 2023: Since this advisory originally published, Cisco has become aware of an issue in a fix for older major Cisco Secure Web Appliance software releases. That issue introduced additional vulnerabilities in releases 14.5.0-537 and 14.5.1-008. Cisco is investigating these new issues and will provide a fix in April 2023 for software releases later than Release 14.5.1-008. These fixes will address all known filter bypass vulnerabilities that are listed in this advisory, as well as the newly found vulnerabilities. Details will be published in this advisory.
A vulnerability in the scanning engines of Cisco AsyncOS Software for Cisco Secure Web Appliance, formerly known as 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.
This vulnerability exists because malformed, encoded traffic is not properly detected. An attacker could exploit this vulnerability 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 this vulnerability. There are no workarounds that address this vulnerability.
This advisory is available at the following link: 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.
Security Impact Rating: Medium
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