CVE-2020-3549: Cisco Secure Firewall Management Center

High severity, CVSS 8.1. EPSS: 1% chance of exploitation in the next 30 days.

A vulnerability in the sftunnel functionality of Cisco Firepower Management Center (FMC) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to obtain the device registration hash. The vulnerability is due to insufficient sftunnel negotiation protection during initial device registration. An attacker in a man-in-the-middle position could exploit this vulnerability by intercepting a specific flow of the sftunnel communication between an FMC device and an FTD device. A successful exploit could allow the attacker to decrypt and modify the sftunnel communication between FMC and FTD devices, allowing the attacker to modify configuration data sent from an FMC device to an FTD device or alert data sent from an FTD device to an FMC device.

Affected products

• Cisco Secure Firewall Management Center: before 6.6.1 (fixed in 6.6.1)
• Cisco Secure Firewall Threat Defense: before 6.6.1 (fixed in 6.6.1)

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