Cisco Firepower Management Center is affected by CVE-2026-20131 (CVSS 9.1, EPSS 73.9th percentile), a command injection vulnerability actively exploited by the Interlock ransomware group in a zero-day campaign that began approximately 36 days before public disclosure. The management plane exposure enables arbitrary OS command execution, lateral movement, and ransomware deployment across managed firewall infrastructure. Immediate action required: restrict FMC management interface network access to authorized hosts only, apply the Cisco-issued patch once the advisory confirms affected version range, rotate all FMC administrative credentials, and ingest Interlock-specific IOCs into SIEM for retrospective hunting.