CVE-2020-3564: Cisco Adaptive Security Appliance

Medium severity, CVSS 5.3. EPSS: 1.3% chance of exploitation in the next 30 days.

A vulnerability in the FTP inspection engine of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass FTP inspection. The vulnerability is due to ineffective flow tracking of FTP traffic. An attacker could exploit this vulnerability by sending crafted FTP traffic through an affected device. A successful exploit could allow the attacker to bypass FTP inspection and successfully complete FTP connections.

Affected products

• Cisco Adaptive Security Appliance: before 9.6 (fixed in 9.6)
• Cisco Adaptive Security Appliance Software: from 9.8.0, before 9.8.4.26 (fixed in 9.8.4.26); from 9.9.0, before 9.9.2.80 (fixed in 9.9.2.80); from 9.10.0, before 9.10.1.44 (fixed in 9.10.1.44); from 9.12.0, before 9.12.4.4 (fixed in 9.12.4.4); from 9.13.0, before 9.13.1.13 (fixed in 9.13.1.13); from 9.14.0, before 9.14.1.19 (fixed in 9.14.1.19)
• Cisco Secure Firewall Threat Defense: before 6.3.0.6 (fixed in 6.3.0.6); from 6.4.0, before 6.4.0.10 (fixed in 6.4.0.10); from 6.5.0, before 6.5.0.5 (fixed in 6.5.0.5); from 6.6.0, before 6.6.1 (fixed in 6.6.1)

Published 2020-10-21. Last modified 2026-08-11.