CVE-2023-20264: 
Cisco Adaptive Security Appliance (ASA) vulnerability analysis and mitigation

A vulnerability in the implementation of Security Assertion Markup Language (SAML) 2.0 single sign-on (SSO) for remote access VPN in Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software was discovered. The vulnerability (CVE-2023-20264) was disclosed on November 1, 2023, affecting ASA Software Release 9.18.3 and FTD Software Release 7.2.4. This vulnerability received a CVSS base score of 6.1 (Medium) (Cisco Advisory).

The vulnerability stems from insufficient validation of the login URL in the SAML 2.0 SSO implementation. The vulnerability is tracked as CWE-601 (URL Redirection to Untrusted Site). It has been assigned a CVSS v3.1 base score of 6.1 (Medium) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N (Cisco Advisory).

A successful exploitation could allow an attacker to intercept a successful SAML assertion and use that assertion to establish a remote access VPN session toward the affected device with the identity and permissions of the hijacked user, resulting in access to the protected network (Cisco Advisory).

Cisco has released software updates that address this vulnerability. There are no workarounds available for this vulnerability. Administrators can determine if remote access VPN services are configured to use SAML 2.0 for authentication by using the show running-config tunnel-group CLI command (Cisco Advisory).