Cisco warns customers of actively exploited zero-day in email gateways

Attackers of unknown origins and motivations are exploiting a critical zero-day vulnerability in Cisco Secure Email Gateway, authorities and researchers said Monday.

The vulnerability — CVE-2026-76461 — was exploited before Cisco disclosed and patched the defect Monday and allows unauthenticated, remote attackers to execute commands with root privileges on vulnerable systems. “In practical terms, that gives the attacker control of the gateway itself,” Douglas McKee, director of vulnerability intelligence at Rapid7, told CyberScoop.

Cisco said its product security incident response team became aware of active exploitation of the defect affecting Cisco AsyncOS Software for Cisco Secure Email Gateway in September. When asked for further details, a company spokesperson pointed to the advisory and reiterated that the company is aware of active exploitation of the vulnerability.