--- id: CVE-2020-3585 title: >- A vulnerability in the TLS handler of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 1000 Series firewalls could allow an unauthenticated, remote attacker to gain ac… summary: >- A vulnerability in the TLS handler of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 1000 Series firewalls could allow an unauthenticated, remote attacker to gain ac… severity: medium cvss: 5.3 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N' cwe: - CWE-203 - CWE-203 vendor: cisco product: secure_firewall_threat_defense affected: - secure_firewall_threat_defense < 6.4.0.10 - 'firepower_threat_defense >= 6.5.0, < 6.5.0.5' - 'firepower_threat_defense >= 6.6.0, < 6.6.1' - adaptive_security_appliance_software < 9.13.1.13 - 'adaptive_security_appliance_software >= 9.14, < 9.14.1.30' patched: - secure_firewall_threat_defense 6.4.0.10 - firepower_threat_defense 6.6.1 - adaptive_security_appliance_software 9.14.1.30 published: '2020-10-21' updated: '2026-08-11' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2020-3585' references: - url: >- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-tls-bb-2g9uWkP label: psirt@cisco.com - url: >- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-tls-bb-2g9uWkP label: af854a3a-2127-422b-91ae-364da2661108 tags: - nvd epss: 0.01254 epssPercentile: 0.68192 ingestedAt: '2026-08-18T12:28:06.714Z' --- ## Overview A vulnerability in the TLS handler of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 1000 Series firewalls could allow an unauthenticated, remote attacker to gain access to sensitive information. The vulnerability is due to improper implementation of countermeasures against the Bleichenbacher attack for cipher suites that rely on RSA for key exchange. An attacker could exploit this vulnerability by sending crafted TLS messages to the device, which would act as an oracle and allow the attacker to carry out a chosen-ciphertext attack. A successful exploit could allow the attacker to perform cryptanalytic operations that may allow decryption of previously captured TLS sessions to the affected device. To exploit this vulnerability, an attacker must be able to perform both of the following actions: Capture TLS traffic that is in transit between clients and the affected device Actively establish a considerable number of TLS connections to the affected device ## Affected - `secure_firewall_threat_defense < 6.4.0.10` - `firepower_threat_defense >= 6.5.0, < 6.5.0.5` - `firepower_threat_defense >= 6.6.0, < 6.6.1` - `adaptive_security_appliance_software < 9.13.1.13` - `adaptive_security_appliance_software >= 9.14, < 9.14.1.30` ## Remediation Upgrade past the affected range: - `secure_firewall_threat_defense 6.4.0.10` - `firepower_threat_defense 6.6.1` - `adaptive_security_appliance_software 9.14.1.30`