Cisco FMC 2026: Interlock Ransomware's Exploitation of Insecure Deserialization
In early 2026, a critical vulnerability (CVE-2026-20131) was discovered in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software. This flaw allowed unauthenticated, remote attackers to execute arbitrary Java code as root by exploiting insecure deserialization of user-supplied Java byte streams. The Interlock ransomware group actively exploited this vulnerability as a zero-day since late January 2026, targeting several high-profile organizations, including DaVita, Kettering Health, the Texas Tech University System, and the city of Saint Paul, Minnesota. The exploitation of CVE-2026-20131 underscores the persistent threat posed by sophisticated ransomware groups leveraging zero-day vulnerabilities. Organizations must prioritize timely patching and robust security measures to mitigate such risks.
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