Cisco Security Advisory
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
Attention: Simplifying the Cisco portfolio includes the renaming of security products under one brand: Cisco Secure. For more information, see Meet Cisco Secure.
At the time of publication, these vulnerabilities affected Cisco Secure Web Appliance, both virtual and hardware versions.
For information about which Cisco software releases were vulnerable at the time of publication, see the Fixed Software section of this advisory. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by these vulnerabilities.
Cisco has confirmed that these vulnerabilities do not affect the following Cisco products:
- Email Security Appliance (ESA), both virtual and hardware appliances
- Secure Email and Web Manager, both virtual and hardware appliances
There are no workarounds that address these vulnerabilities.
When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories page, to determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
At the time of publication, the release information in the following table was accurate. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
The left column lists Cisco software releases, and the right column indicates whether a release was affected by the vulnerabilities that are described in this advisory and which release included the fix for these vulnerabilities.
Cisco AsyncOS Release First Fixed Release 11.7 and earlier Not vulnerable. 11.8 Migrate to a fixed release. 12.0 Migrate to a fixed release. 12.5 Migrate to a fixed release. 14.0 14.0.4 14.5 14.5.1-016
The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.
The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerabilities that are described in this advisory.
Cisco would like to thank scanplus GmbH for reporting these vulnerabilities.
To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
Version Description Section Status Date 2.0 Added CVE-2023-20099. Added Cisco bug ID CSCwe16408. Updated the summary and the fixed release table. Header, Summary, Fixed Releases Final 2023-APR-03 1.2 Added details about newly introduced vulnerabilities and future fix plans for those vulnerabilities. Summary Final 2023-MAR-02 1.1 Added fixed release information. Added references to the Fixed Software section. Summary, Vulnerable Products, Fixed Software. Final 2023-FEB-15 1.0 Initial public release. - Final 2022-OCT-05
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