CVE-2020-3557: Cisco Secure Firewall Management Center

Medium severity, CVSS 5.3. EPSS: 0.7% chance of exploitation in the next 30 days.

A vulnerability in the host input API daemon of Cisco Firepower Management Center (FMC) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper certificate validation. An attacker could exploit this vulnerability by sending a crafted data stream to the host input daemon of the affected device. A successful exploit could allow the attacker to cause the host input daemon to restart. The attacker could use repeated attacks to cause the daemon to continuously reload, creating a DoS condition for the API.

Affected products

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

Published 2020-10-21. Last modified 2026-06-17.