{"id":"CVE-2020-3562","title":"A vulnerability in the SSL/TLS inspection of Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 2100 Series firewalls could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affec…","summary":"A vulnerability in the SSL/TLS inspection of Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 2100 Series firewalls could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affec…","severity":"high","cvss":8.6,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H","cwe":["CWE-119","CWE-119"],"vendor":"cisco","product":"secure_firewall_threat_defense","affected":["secure_firewall_threat_defense = 6.3.0","secure_firewall_threat_defense = 6.4.0","secure_firewall_threat_defense = 6.5.0"],"published":"2020-10-21","updated":"2026-08-11","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2020-3562","references":[{"url":"https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-ssl-dcrpt-dos-RYEkX4yy","label":"psirt@cisco.com"},{"url":"https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-ssl-dcrpt-dos-RYEkX4yy","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.0181,"epssPercentile":0.77326,"ingestedAt":"2026-08-11T19:48:28.875Z","slug":"CVE-2020-3562","body":"## Overview\n\nA vulnerability in the SSL/TLS inspection of Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 2100 Series firewalls could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper input validation for certain fields of specific SSL/TLS messages. An attacker could exploit this vulnerability by sending a malformed SSL/TLS message through an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. No manual intervention is needed to recover the device after it has reloaded.\n\n## Affected\n\n- `secure_firewall_threat_defense = 6.3.0`\n- `secure_firewall_threat_defense = 6.4.0`\n- `secure_firewall_threat_defense = 6.5.0`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":47.3,"likelihood":0.4,"exploitation":0,"ransomware":0},"changes":[]}