// #fmc

Interlock Ransomware Exploited Cisco FMC Zero-Day for 36 Days Before Patch — Root Access on Enterprise Firewalls

Cisco's Firepower Management Center (FMC) contains a CVSS 10.0 deserialization vulnerability that Interlock ransomware was exploiting as a zero-day for 36 days before Cisco disclosed or patched it. CVE-2026-20131 allows unauthenticated remote attackers to execute arbitrary Java code as root on any internet-exposed FMC appliance. Cisco patched the flaw on 4 March 2026, but unpatched appliances remain under active ransomware targeting.