CVE-2026-20343: Cisco Secure Firewall Management Center FMC

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

A vulnerability in a critical API for Cisco Secure FMC Software could allow an unauthenticated, remote attacker to download sensitive files and use unbounded disk space. This vulnerability exists because a critical API lacks authentication. An attacker could exploit this vulnerability by repeatedly invoking the API. A successful exploit could allow the attacker to download sensitive files that should be restricted and consume disk space so the device could become unresponsive, causing a DoS condition.

Affected products

• Cisco Cisco Secure Firewall Management Center FMC: version 7.3.0 only; version 7.3.1 only; version 7.3.1.1 only; version 7.4.0 only; version 7.4.1 only; version 7.4.1.1 only; …

Published 2026-09-16. Last modified 2026-09-18.