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

A vulnerability in the Internet Key Exchange Version 2 (IKEv2) feature of Cisco IOS Software, IOS XE Software, Secure Firewall ASA Software, and Secure FTD Software was discovered and disclosed on August 14, 2025. The vulnerability, identified as CVE-2025-20253, could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition by forcing the device to reload. This high-severity vulnerability affects multiple Cisco products that have the IKEv2 VPN feature enabled, including IOS Software, IOS XE Software, Secure Firewall ASA Software, and Secure FTD Software (Cisco Advisory).

The vulnerability stems from improper processing of IKEv2 packets in affected systems. It has been assigned a CVSS base score of 8.6 (High) with the vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H. The technical analysis reveals that the vulnerability can trigger an infinite loop condition that exhausts system resources. The vulnerability is tracked under CWE-835 (Loop with Unreachable Exit Condition) and CWE-401 (Cisco Advisory).

A successful exploitation of this vulnerability results in a denial of service condition where the affected device enters an infinite loop that exhausts system resources, ultimately causing the device to reload. This impact is particularly significant for network infrastructure devices where availability is crucial (Cisco Advisory).

Cisco has released software updates that address this vulnerability. There are no workarounds available for this vulnerability. Organizations using affected products should upgrade to the fixed software versions through their regular update channels. The vulnerability can be identified on Cisco devices by using the show ip socket | include 500 or show udp | include 500 EXEC commands to determine if IKE processing is enabled, followed by the show crypto map command to verify IKEv2 usage (Cisco Advisory).