The Interlock ransomware group had a one-month head start on your defense team. 🛡️
CVE-2026-20131 · Severity 10.0 · Critical Java Deserialization in Cisco Secure FMC.
Amazon Threat Intelligence has confirmed that the Interlock ransomware group has been weaponizing a critical flaw in @[Cisco]\\(urn:li:organization:1063\\) Secure Firewall Management Center ❨FMC❩ since January 26‚ 2026. This unauthenticated RCE allows attackers to bypass authentication and execute Java code as root.
The vulnerability stems from insecure deserialization of user-supplied Java byte streams. Because FMC manages your entire firewall estate‚ root access here allows an attacker to dismantle network security controls and deploy ransomware globally from a single trusted node.
The uncomfortable truth: Your perimeter security tools are now the primary vehicles for automated ransomware delivery because they often operate with the highest privileges and the least oversight.
→ Update Cisco Secure Firewall Management Center to the latest patched version immediately.
→ Strictly isolate all management plane interfaces from the public internet using a secure VPN or OOB management network.
→ Audit your FMC logs for unauthorized administrative accounts or anomalous Java process executions dating back to January.
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