{"id":"CVE-2021-40125","aliases":["EUVD-2021-27312","GHSA-cg2g-27wj-x8x6"],"status":"published","title":"Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software IKEv2 Site-to-Site VPN Denial of Service Vulnerability","description":"A vulnerability in the Internet Key Exchange Version 2 (IKEv2) implementation of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker to trigger a denial of service (DoS) condition on an affected device. This vulnerability is due to improper control of a resource. An attacker with the ability to spoof a trusted IKEv2 site-to-site VPN peer and in possession of valid IKEv2 credentials for that peer could exploit this vulnerability by sending malformed, authenticated IKEv2 messages to an affected device. A successful exploit could allow the attacker to trigger a reload of the device.","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.01024,"percentile":0.63931,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-400","CWE-416"],"published":"2021-10-27T18:50:09Z","modified":"2026-08-11T19:37:30Z","products":[{"vendor":"cisco","product":"adaptive_security_appliance_software"},{"vendor":"cisco","product":"asa_5505_firmware"},{"vendor":"cisco","product":"asa_5512-x_firmware"},{"vendor":"cisco","product":"asa_5515-x_firmware"},{"vendor":"cisco","product":"asa_5525-x_firmware"},{"vendor":"cisco","product":"asa_5545-x_firmware"},{"vendor":"cisco","product":"asa_5555-x_firmware"},{"vendor":"cisco","product":"asa_5580_firmware"},{"vendor":"cisco","product":"asa_5585-x_firmware"},{"vendor":"cisco","product":"cisco adaptive security appliance (asa) software"},{"vendor":"cisco","product":"secure_firewall_threat_defense"}],"references":[{"url":"https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ikev2-dos-g4cmrr7C","tags":["vendor-advisory","x_refsource_CISCO","x_transferred","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-40125"},{"url":"https://github.com/advisories/GHSA-cg2g-27wj-x8x6"}],"sources":{"cve":[{"id":"CVE-2021-40125","title":"Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software IKEv2 Site-to-Site VPN Denial of Service Vulnerability","description":"A vulnerability in the Internet Key Exchange Version 2 (IKEv2) implementation of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker to trigger a denial of service (DoS) condition on an affected device. This vulnerability is due to improper control of a resource. An attacker with the ability to spoof a trusted IKEv2 site-to-site VPN peer and in possession of valid IKEv2 credentials for that peer could exploit this vulnerability by sending malformed, authenticated IKEv2 messages to an affected device. A successful exploit could allow the attacker to trigger a reload of the device.","status":"published","published":"2021-10-27T18:50:09.794Z","modified":"2024-11-07T21:46:26.254Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-416"],"updated_at":"2026-11-02T14:33:01.495293Z"}],"euvd":[{"id":"EUVD-2021-27312","description":"A vulnerability in the Internet Key Exchange Version 2 (IKEv2) implementation of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker to trigger a denial of service (DoS) condition on an affected device. This vulnerability is due to improper control of a resource. An attacker with the ability to spoof a trusted IKEv2 site-to-site VPN peer and in possession of valid IKEv2 credentials for that peer could exploit this vulnerability by sending malformed, authenticated IKEv2 messages to an affected device. A successful exploit could allow the attacker to trigger a reload of the device.","status":"published","published":"2021-10-27T18:50:09Z","modified":"2024-11-07T21:46:26Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-03T00:05:07.826667Z"}],"ghsa":[{"id":"GHSA-cg2g-27wj-x8x6","title":"A vulnerability in the Internet Key Exchange Version 2 (IKEv2) implementation of Cisco Adaptive...","description":"A vulnerability in the Internet Key Exchange Version 2 (IKEv2) implementation of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker to trigger a denial of service (DoS) condition on an affected device. This vulnerability is due to improper control of a resource. An attacker with the ability to spoof a trusted IKEv2 site-to-site VPN peer and in possession of valid IKEv2 credentials for that peer could exploit this vulnerability by sending malformed, authenticated IKEv2 messages to an affected device. A successful exploit could allow the attacker to trigger a reload of the device.","status":"published","published":"2022-05-24T19:18:53Z","modified":"2023-08-25T05:02:34Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-400","CWE-416"],"updated_at":"2026-11-02T14:54:45.82233Z"}],"nvd":[{"id":"CVE-2021-40125","description":"A vulnerability in the Internet Key Exchange Version 2 (IKEv2) implementation of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, remote attacker to trigger a denial of service (DoS) condition on an affected device. This vulnerability is due to improper control of a resource. An attacker with the ability to spoof a trusted IKEv2 site-to-site VPN peer and in possession of valid IKEv2 credentials for that peer could exploit this vulnerability by sending malformed, authenticated IKEv2 messages to an affected device. A successful exploit could allow the attacker to trigger a reload of the device.","status":"published","published":"2021-10-27T19:15:08.877Z","modified":"2026-08-11T19:37:30.88Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"primary"},{"version":"2.0","score":6.3,"vector":"AV:N/AC:M/Au:S/C:N/I:N/A:C","level":"medium","assessor":"primary"}],"cwes":["CWE-416","CWE-400"],"updated_at":"2026-11-02T14:07:00.549994Z"}]}}