CVE-2025-20263: 
Cisco Adaptive Security Appliance (ASA) vulnerability analysis and mitigation

A vulnerability in the web services interface of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software was discovered and disclosed on August 14, 2025. The vulnerability, identified as CVE-2025-20263, affects the web services interface of these systems and could allow an unauthenticated, remote attacker to cause a buffer overflow condition (Cisco Advisory).

The vulnerability stems from insufficient boundary checks for specific data provided to the web services interface of affected systems. It has been assigned a CVSS base score of 8.6 (High severity) with the following vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X. The vulnerability is tracked under CWE-680 and Cisco Bug ID CSCwn21584 (Cisco Advisory).

A successful exploitation of this vulnerability could allow an attacker to cause a buffer overflow condition on the affected system, which could result in the system reloading and creating a denial of service (DoS) condition. This impacts the availability of critical security infrastructure, potentially disrupting network operations (Cisco Advisory).

Cisco has released software updates that address this vulnerability. There are no workarounds available for this vulnerability. Customers with service contracts can obtain security fixes through their usual update channels. Those without service contracts should contact the Cisco Technical Assistance Center (TAC) for assistance (Cisco Advisory).