Secure Firewall ASA and FTD
CVE-2026-20250: Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software for Firepower 3100 and 4200 Series DTLS Denial of Service Vulnerability
A vulnerability in Datagram TLS (DTLS) message handling of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software for Cisco Secure Firewall 3100 Series and 4200 Series devices could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.
Published
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.24 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.6 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.7 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.6 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.6 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.7 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.7 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.6 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.7 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.6 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 10.0 | See the advisory |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
A vulnerability in Datagram TLS (DTLS) message handling of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software for Cisco Secure Firewall 3100 Series and 4200 Series devices could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.
This vulnerability is due to improper resource management when processing certain DTLS messages. An attacker could exploit this vulnerability by sending a crafted stream of DTLS traffic to an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.
Exploitation
The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 11 Oct 2026.