CVE-2020-3549: A vulnerability in the sftunnel functionality of Cisco Firepower Management Center (FMC) Software and Cisco Firepower Threat Defense (FTD) Software co...

Description

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.

Metrics

CVSS 3.1

8.1/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.93%

56.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Cisco	Firepower Threat Defense	< 6.6.1
Cisco	Secure Firewall Management Center	< 6.6.1

References

Timeline

Published: Oct 21, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-3549?

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.

How severe is CVE-2020-3549?

CVE-2020-3549 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 0.93% probability of exploitation in the next 30 days.

How do I fix CVE-2020-3549?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.