Cisco Warns of Actively Exploited Zero-Day Vulnerability in Secure Email Gateway (CVE-2026-76461)

Cisco has issued a warning regarding a critical zero-day vulnerability, CVE-2026-76461, in its AsyncOS Software for Cisco Secure Email Gateway, which is currently under active exploitation. The flaw, with a CVSS score of 9.8, stems from insufficient validation in the email parsing logic, enabling unauthenticated, remote attackers to execute arbitrary commands with root privileges. CISA has added this vulnerability to its Known Exploited Vulnerabilities catalog, urging federal agencies to apply patches by September 17, 2026.