{"id":"CVE-2021-40117","aliases":["EUVD-2021-27304","GHSA-x7cf-699f-fpwc"],"status":"published","title":"Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software SSL/TLS Denial of Service Vulnerability","description":"A vulnerability in SSL/TLS message handler for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because incoming SSL/TLS packets are not properly processed. An attacker could exploit this vulnerability by sending a crafted SSL/TLS packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.","severity":{"version":"3.1","score":8.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.01729,"percentile":0.77883,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-119","CWE-400"],"published":"2021-10-27T18:56:48Z","modified":"2026-08-11T19:37:30Z","products":[{"vendor":"cisco","product":"adaptive_security_appliance"},{"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-dos-4ygzLKU9","tags":["vendor-advisory","x_refsource_CISCO","x_transferred","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-40117"},{"url":"https://github.com/advisories/GHSA-x7cf-699f-fpwc"}],"sources":{"cve":[{"id":"CVE-2021-40117","title":"Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software SSL/TLS Denial of Service Vulnerability","description":"A vulnerability in SSL/TLS message handler for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because incoming SSL/TLS packets are not properly processed. An attacker could exploit this vulnerability by sending a crafted SSL/TLS packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.","status":"published","published":"2021-10-27T18:56:48.507Z","modified":"2024-11-07T21:45:24.364Z","cvss":[{"version":"3.1","score":8.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-119"],"updated_at":"2026-11-02T14:33:01.852999Z"}],"euvd":[{"id":"EUVD-2021-27304","description":"A vulnerability in SSL/TLS message handler for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because incoming SSL/TLS packets are not properly processed. An attacker could exploit this vulnerability by sending a crafted SSL/TLS packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.","status":"published","published":"2021-10-27T18:56:48Z","modified":"2024-11-07T21:45:24Z","cvss":[{"version":"3.1","score":8.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-03T00:05:07.826667Z"}],"ghsa":[{"id":"GHSA-x7cf-699f-fpwc","title":"A vulnerability in SSL/TLS message handler for Cisco Adaptive Security Appliance (ASA) Software...","description":"A vulnerability in SSL/TLS message handler for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because incoming SSL/TLS packets are not properly processed. An attacker could exploit this vulnerability by sending a crafted SSL/TLS packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.","status":"published","published":"2022-05-24T19:18:53Z","modified":"2023-08-16T18:30:20Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-119","CWE-400"],"updated_at":"2026-11-02T14:54:45.250925Z"}],"nvd":[{"id":"CVE-2021-40117","description":"A vulnerability in SSL/TLS message handler for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because incoming SSL/TLS packets are not properly processed. An attacker could exploit this vulnerability by sending a crafted SSL/TLS packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.","status":"published","published":"2021-10-27T19:15:08.77Z","modified":"2026-08-11T19:37:30.88Z","cvss":[{"version":"3.1","score":8.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H","level":"high","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"},{"version":"2.0","score":7.8,"vector":"AV:N/AC:L/Au:N/C:N/I:N/A:C","level":"high","assessor":"primary"}],"cwes":["CWE-119","CWE-400"],"updated_at":"2026-11-02T14:07:00.549994Z"}]}}