{"id":"CVE-2023-20042","aliases":["EUVD-2023-24221","GHSA-2c63-fqw2-3fhm"],"status":"published","title":"A vulnerability in the AnyConnect SSL VPN feature of Cisco Adaptive Security Appliance (ASA)...","description":"A vulnerability in the AnyConnect SSL VPN feature of 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 is due to an implementation error within the SSL/TLS session handling process that can prevent the release of a session handler under specific conditions. An attacker could exploit this vulnerability by sending crafted SSL/TLS traffic to an affected device, increasing the probability of session handler leaks. A successful exploit could allow the attacker to eventually deplete the available session handler pool, preventing new sessions from being established and causing a DoS condition.","severity":{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00903,"percentile":0.60207,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-404"],"published":"2023-11-01T17:11:08Z","modified":"2026-08-11T19:33:44Z","products":[{"vendor":"cisco","product":"adaptive_security_appliance_software"},{"vendor":"cisco","product":"cisco adaptive security appliance (asa) software"},{"vendor":"cisco","product":"cisco firepower threat defense software"},{"vendor":"cisco","product":"secure_firewall_threat_defense"}],"references":[{"url":"https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ssl-dos-kxG8mpUA","tags":["x_transferred","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-20042"},{"url":"https://github.com/advisories/GHSA-2c63-fqw2-3fhm"}],"sources":{"cve":[{"id":"CVE-2023-20042","description":"A vulnerability in the AnyConnect SSL VPN feature of 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 is due to an implementation error within the SSL/TLS session handling process that can prevent the release of a session handler under specific conditions. An attacker could exploit this vulnerability by sending crafted SSL/TLS traffic to an affected device, increasing the probability of session handler leaks. A successful exploit could allow the attacker to eventually deplete the available session handler pool, preventing new sessions from being established and causing a DoS condition.","status":"published","published":"2023-11-01T17:11:08.109Z","modified":"2024-08-02T08:57:35.839Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-404"],"updated_at":"2026-11-02T14:35:13.368958Z"}],"euvd":[{"id":"EUVD-2023-24221","description":"A vulnerability in the AnyConnect SSL VPN feature of 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 is due to an implementation error within the SSL/TLS session handling process that can prevent the release of a session handler under specific conditions. An attacker could exploit this vulnerability by sending crafted SSL/TLS traffic to an affected device, increasing the probability of session handler leaks. A successful exploit could allow the attacker to eventually deplete the available session handler pool, preventing new sessions from being established and causing a DoS condition.","status":"published","published":"2023-11-01T17:11:08Z","modified":"2024-08-02T08:57:35Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-03T03:50:09.688494Z"}],"ghsa":[{"id":"GHSA-2c63-fqw2-3fhm","title":"A vulnerability in the AnyConnect SSL VPN feature of Cisco Adaptive Security Appliance (ASA)...","description":"A vulnerability in the AnyConnect SSL VPN feature of 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 is due to an implementation error within the SSL/TLS session handling process that can prevent the release of a session handler under specific conditions. An attacker could exploit this vulnerability by sending crafted SSL/TLS traffic to an affected device, increasing the probability of session handler leaks. A successful exploit could allow the attacker to eventually deplete the available session handler pool, preventing new sessions from being established and causing a DoS condition.","status":"published","published":"2023-11-01T18:30:33Z","modified":"2024-01-25T18:30:47Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-404"],"updated_at":"2026-11-02T14:55:29.01801Z"}],"nvd":[{"id":"CVE-2023-20042","description":"A vulnerability in the AnyConnect SSL VPN feature of 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 is due to an implementation error within the SSL/TLS session handling process that can prevent the release of a session handler under specific conditions. An attacker could exploit this vulnerability by sending crafted SSL/TLS traffic to an affected device, increasing the probability of session handler leaks. A successful exploit could allow the attacker to eventually deplete the available session handler pool, preventing new sessions from being established and causing a DoS condition.","status":"published","published":"2023-11-01T18:15:08.843Z","modified":"2026-08-11T19:33:44.513Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H","level":"medium","assessor":"secondary"},{"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":"primary"}],"cwes":["CWE-404"],"updated_at":"2026-11-02T14:08:41.047232Z"}]}}