CVE-2026-20250 describes a vulnerability in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software specifically for the 3100 and 4200 Series devices. The issue stems from improper resource management when processing certain Datagram TLS (DTLS) messages. An unauthenticated remote attacker can exploit this by sending a crafted stream of DTLS traffic, causing the affected device to reload and resulting in a denial of service condition. The CVSS v3.1 base score is 8.6 (high severity) with an attack vector of network, low attack complexity, no privileges or user interaction required, and scope changed. The impact is limited to availability (denial of service), with no confidentiality or integrity impact reported.

Successful exploitation results in a denial of service condition by forcing the affected Cisco Secure Firewall device to reload. This disrupts network security operations on the affected device. There is no reported impact on confidentiality or integrity.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Until a patch is available, monitor for unusual DTLS traffic and consider network-level controls to limit exposure to untrusted sources sending DTLS traffic to affected devices.