Description

Cisco has reported ongoing attacks targeting a zero-day vulnerability in the Advanced Malware Protection (AMP) component of Cisco Secure Email Gateway. The security issue could allow remote attackers to gain root-level access to affected systems by writing arbitrary files and executing operating system commands without authentication. Cisco’s PSIRT confirmed active exploitation of the vulnerability in October 2026. A CVE number and CVSS severity score have not yet been specified. The vulnerability is associated with the way email attachments are processed when the File Reputation service is enabled. An attacker can exploit the weakness by sending a specially crafted email containing a malicious attachment through a vulnerable gateway. The attack does not require valid credentials or any action from the recipient. The issue affects physical and virtual Cisco Secure Email Gateway appliances when File Reputation is enabled and assigned to a mail policy, and the Content Scanner Tools version is earlier than 25.3.0.5525. Cisco Secure Email and Web Manager and Cisco Secure Web Appliance are not affected by this vulnerability. If exploited successfully, the flaw could give attackers extensive control over the compromised appliance. They may be able to alter system files, execute malicious commands, erase evidence of intrusion, and interfere with security monitoring. In clustered environments, attackers could potentially use stolen SSH private keys to access other appliances, increasing the risk of a wider compromise.