What it is about

Die Cisco ASA Appliance bietet Funktionen zur Sicherung von Anwendungssoftware, wie beispielsweise Firewall oder VPN. Cisco Secure Firewall Threat Defense ist eine Sicherheitslösung, die Funktionen wie Firewall, Intrusion Prevention und erweiterten Malware-Schutz in einer einzigen Appliance integriert. Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Cisco ASA (Adaptive Security Appliance) und Cisco Secure Firewall Threat Defense ausnutzen, um einen Denial of Service Angriff durchzuführen.

Under what conditions?

Over the network and without logging in. This is the most dangerous combination: attackers can scan reachable devices automatically.

What can happen in the worst case

An attacker could use the vulnerability to

• einen Denial of Service Angriff durchzuführen

Am I affected?

Affected according to the BSI:

• Cisco ASA (Adaptive Security Appliance) <89.16.4.50
• Cisco ASA (Adaptive Security Appliance) <89.18.4.50
• Cisco ASA (Adaptive Security Appliance) <9.20.4.235
• Cisco ASA (Adaptive Security Appliance) <9.22.3.191
• Cisco ASA (Adaptive Security Appliance) <9.23.1.211
• Cisco ASA (Adaptive Security Appliance) <9.24.1.221
• Cisco Secure Firewall Threat Defense

The installed version is usually shown under “Help → About” or in the device’s admin interface.

What helps?

Update to at least:

• Cisco ASA (Adaptive Security Appliance) 89.16.4.50
• Cisco ASA (Adaptive Security Appliance) 89.18.4.50
• Cisco ASA (Adaptive Security Appliance) 9.20.4.235
• Cisco ASA (Adaptive Security Appliance) 9.22.3.191
• Cisco ASA (Adaptive Security Appliance) 9.23.1.211
• Cisco ASA (Adaptive Security Appliance) 9.24.1.221

Is the vulnerability already being exploited?

• CVE-2026-20349: exploited in the wild according to CISA, in the catalogue since 11.08.2026.