CVE-2023-20256: Cisco Adaptive Security Appliance Software

Medium severity, CVSS 5.8. EPSS: 0.6% chance of exploitation in the next 30 days.

Multiple vulnerabilities in the per-user-override feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass a configured access control list (ACL) and allow traffic that should be denied to flow through an affected device. These vulnerabilities are due to a logic error that could occur when the affected software constructs and applies per-user-override rules. An attacker could exploit these vulnerabilities by connecting to a network through an affected device that has a vulnerable configuration. A successful exploit could allow the attacker to bypass the interface ACL and access resources that would should be protected.

Affected products

• Cisco Adaptive Security Appliance Software: version 9.8.4.22 only; version 9.8.4.25 only; version 9.8.4.26 only; version 9.8.4.29 only; version 9.8.4.32 only; version 9.8.4.33 only; …
• Cisco Secure Firewall Threat Defense: version 6.2.3.16 only; version 6.2.3.17 only; version 6.2.3.18 only; version 6.4.0.10 only; version 6.4.0.11 only; version 6.4.0.12 only; …

Published 2023-11-01. Last modified 2026-08-11.