CVE-2025-20253: 
Cisco Adaptive Security Appliance (ASA) vulnerability analysis and mitigation

A vulnerability (CVE-2025-20253) has been identified in the Internet Key Exchange Version 2 (IKEv2) feature of Cisco IOS Software, IOS XE Software, Secure Firewall ASA Software, and Secure FTD Software. The vulnerability, discovered by Jason Crowder of the Cisco Advanced Security Initiatives Group (ASIG), was disclosed on August 14, 2025. This security flaw affects devices with the IKEv2 VPN feature enabled, potentially allowing an unauthenticated, remote attacker to cause a denial of service (DoS) condition (Cisco Advisory).

The vulnerability stems from improper processing of IKEv2 packets, which can lead to an infinite loop condition (CWE-835). The vulnerability has been assigned a CVSS Base Score of 8.6 (High) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H, indicating network accessibility, low attack complexity, and no required privileges or user interaction (NVD).

A successful exploitation of this vulnerability could allow an attacker to cause the affected device to enter an infinite loop that exhausts system resources, ultimately resulting in a device reload. This creates a denial of service (DoS) condition, disrupting network operations and requiring manual intervention to restore services (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) (Cisco Advisory).