CVE-2026-20023: Cisco Adaptive Security Appliance Software

Medium severity, CVSS 6.5. EPSS: 0.2% chance of exploitation in the next 30 days.

A vulnerability in the OSPF protocol of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, adjacent attacker to corrupt memory on an affected device, resulting in a denial of service (DoS) condition. This vulnerability is due to memory corruption when parsing OSPF protocol packets. An attacker could exploit this vulnerability by sending crafted OSPF packets to an affected device. A successful exploit could allow the attacker to cause memory corruption causing the affected device to reboot, resulting in a DoS condition.

Affected products

• Cisco Adaptive Security Appliance Software: version 9.12.1 only; version 9.12.1.2 only; version 9.12.1.3 only; version 9.12.2 only; version 9.12.2.1 only; version 9.12.2.4 only; …
• Cisco Secure Firewall Threat Defense: version 6.4.0 only; version 6.4.0.1 only; version 6.4.0.2 only; version 6.4.0.3 only; version 6.4.0.4 only; version 6.4.0.5 only; …

Published 2026-03-04. Last modified 2026-08-11.