Cisco Secure Firewall Adaptive Security Appliance Software DTLS Message resource consumption

Summaryinfo

A vulnerability, which was classified as critical, was found in Cisco Secure Firewall Adaptive Security Appliance Software and Secure Firewall Threat Defense Software. This impacts an unknown function of the component DTLS Message Handler. Such manipulation leads to resource consumption. This vulnerability is traded as CVE-2026-20250. The attack may be launched remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Cisco Secure Firewall Adaptive Security Appliance Software and Secure Firewall Threat Defense Software (affected version not known) and classified as critical. Affected by this issue is some unknown functionality of the component DTLS Message Handler. The manipulation with an unknown input leads to a resource consumption vulnerability. Using CWE to declare the problem leads to CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Impacted is availability. CVE summarizes:

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.

The advisory is shared for download at sec.cloudapps.cisco.com. This vulnerability is handled as CVE-2026-20250 since 10/08/2025. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/16/2026). The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading eliminates this vulnerability.

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Productinfo

Type

• Firewall Software

Vendor

• Cisco

Name

• Secure Firewall Adaptive Security Appliance Software
• Secure Firewall Threat Defense Software

License

• commercial

Website

• Vendor: https://www.cisco.com/

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