Cisco Warns of New Zero-Day ISE Auth Bypass (CVSS 10.0) Exploited in Active Attacks

Cisco warns CVE-2026-76460 (CVSS 10.0), an unauthenticated ISE auth bypass leading to root command execution, is under active exploitation and was added to CISA's KEV.

Cisco warned that CVE-2026-76460 (CVSS 10.0), an insufficient-authentication flaw in an Identity Services Engine (ISE) API endpoint, is being actively exploited by unauthenticated remote attackers and can yield root-privilege command execution on ISE and ISE-PIC regardless of configuration. Fixes shipped across ISE 3.1 through 3.5 patch branches; Cisco advised reviewing access.log for unexpected usernames (e.g., "dummyuser"), re-imaging affected nodes, and using iACLs, since no workarounds exist. CISA added the flaw to its KEV catalog on September 16, 2026, requiring FCEB agencies to patch by September 19. Cisco simultaneously issued 77 new CVEs, 41 affecting ISE and 28 affecting Secure Firewall products, days after confirming active exploitation of CVE-2026-76461 in Secure Email Gateway.