Cisco patches Secure Email Gateway zero-day exploited in attacks

Cisco warned customers to patch a critical Secure Email Gateway zero-day security flaw that threat actors have been exploiting in attacks.

"In September 2026, the Cisco PSIRT became aware of active exploitation of this vulnerability," the company warned in a Monday security advisory.

The security flaw (tracked as CVE-2026-76461) was found in the email parsing of Cisco AsyncOS Software for Cisco Secure Email Gateway and affects virtual and physical appliances, regardless of the device configuration.

Successful exploitation can allow unauthenticated, remote attackers to execute arbitrary commands with root privileges on the underlying operating system.

"This vulnerability is due to insufficient validation in the email parsing logic. An attacker could exploit this vulnerability by sending a crafted email message that contains malicious SQL statements through an affected device," Cisco added. "A successful exploit could allow the attacker to execute arbitrary SQL statements, leading to command execution with root privileges on the underlying operating system."