CVE-2026-20250 Denial of service in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
Unauthenticated remote attackers can cause a denial of service on Cisco Secure Firewall ASA and FTD devices by sending crafted DTLS traffic.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-20250?
CVE-2026-20250 is a high-severity denial of service vulnerability in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-772
Which versions are affected by CVE-2026-20250?
How do I fix CVE-2026-20250?
No fix has been published for CVE-2026-20250 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-20250 being exploited?
There is no known exploitation of CVE-2026-20250 in the wild and no public exploit code.
Sources
Also known as GHSA-rf4g-28mq-c9qr.