Cisco Systems has disclosed a critical vulnerability affecting its Cisco Secure Email Gateway email security product. The flaw, identified as CVE-2026-76519, resides in the Advanced Malware Protection (AMP) component that handles email attachment processing.
Attackers can exploit the issue by sending a specially crafted email containing a malicious attachment. No authentication is required, and successful exploitation allows arbitrary files to be written on the underlying operating system. This can ultimately enable attackers to execute commands with root privileges.
The vulnerability carries a CVSS v3.1 base score of 9.8, placing it in the highest severity category of Critical. Cisco published the official security advisory on October 14, 2026, and confirmed that exploitation had already been observed in the wild during the same month.
This marks the second instance of an exploited vulnerability in Cisco email security products being publicly disclosed in recent weeks, although the company states the issues are distinct.
