A newly disclosed vulnerability in Cisco’s implementation of the Internet Key Exchange version 2 (IKEv2) protocol could allow remote attackers to crash affected network devices. The vulnerability, tracked as CVE-2025-20182 with a CVSS score of 8.6, affects multiple Cisco products including Adaptive Security Appliance (ASA) Software, Firepower Threat Defense (FTD) Software, IOS Software, and IOS XE Software1.
Technical Overview
The vulnerability stems from insufficient input validation when processing IKEv2 messages. An unauthenticated attacker can exploit this flaw by sending specially crafted IKEv2 packets to vulnerable devices. Successful exploitation causes the affected device to reload, resulting in a denial of service condition. The attack requires no authentication and can be executed remotely, making it particularly dangerous for internet-facing devices2.
Cisco has confirmed the vulnerability affects multiple product lines, but notably excludes IOS XR, Meraki, and NX-OS platforms. The company has released software updates to address the issue and recommends immediate patching for affected systems. Network administrators can verify their device’s vulnerability status using Cisco’s Software Checker tool3.
Detection and Mitigation
For organizations unable to immediately patch, detection methods include monitoring for anomalous IKEv2 traffic. On ASA/FTD devices, administrators can check IKEv2 configuration with the command show running-config crypto ikev2 | include enable. IOS/IOS XE users should examine UDP ports 500 and 4500 using show udp and show running-config | include ikev22.
Cisco has stated there are no viable workarounds for this vulnerability, as disabling IKEv2 would disrupt VPN functionality. The company emphasizes that patching is the only complete solution. Organizations should prioritize updating affected devices, particularly those exposed to untrusted networks.
Security Implications
This vulnerability presents significant risks for organizations relying on Cisco devices for network security and remote access. The ability to cause a DoS condition remotely could be leveraged in targeted attacks to disrupt operations or as part of a larger attack chain. The lack of authentication requirements lowers the barrier for exploitation.
Historical context shows similar IKEv2 vulnerabilities have been discovered in other Cisco products, including CVE-2025-20209 in IOS XR earlier this year. This pattern suggests ongoing scrutiny of Cisco’s VPN implementations by security researchers2.
Conclusion
CVE-2025-20182 represents a serious threat to organizations using affected Cisco devices, particularly those with internet-facing VPN services. The high CVSS score reflects the potential impact of successful exploitation. Network administrators should immediately assess their exposure, apply available patches, and monitor for suspicious IKEv2 traffic. Cisco’s Security Advisory provides complete details on fixed software versions and additional mitigation guidance1.
References
- “Cisco Security Advisory: Multiple Products IKEv2 Denial of Service Vulnerability,” Cisco Systems, May 7, 2025. [Online]. Available: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-multiprod-ikev2-dos-gPctUqv2
- “GitHub Advisory: Cisco IKEv2 Denial of Service Vulnerabilities,” GitHub Security, May 7, 2025. [Online]. Available: https://github.com/advisories/GHSA-gv7m-f47c-w86q
- “Vulnerability Details: CVE-2025-20182,” SecAlerts, May 7, 2025. [Online]. Available: https://secalerts.co/vulnerability/CVE-2025-20182
