Three threat clusters exploit Cisco Secure FMC flaws to steal credentials and deploy Qilin ransomware

Cisco Talos identified three distinct clusters exploiting CVE-2026-20079, a CVSS 10.0 authentication bypass in Cisco Secure Firewall Management Center, alongside the lower-severity CVE-2026-20316. UAT-12197 deployed JSP web shells and Java command executors to harvest credentials and authentication data from internal databases; UAT-11823 delivered reverse shells and configuration harvesting scripts and deployed Cyclops Blink, previously attributed to Russian state-sponsored Sandworm; UAT-11988 used legitimate FMC tooling for reconnaissance and credential collection before deploying Qilin ransomware. CISA added CVE-2026-20079 to the KEV catalog on 9 September 2026 with a 12 September federal deadline.