CVE-2026-76461 in AsyncOS
Summary
by MITRE • 09/14/2026
A vulnerability in the email parsing of Cisco AsyncOS Software for Cisco Secure Email Gateway could allow an unauthenticated, remote attacker 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. A successful exploit could allow the attacker to execute arbitrary SQL statements, leading to command execution with root privileges on the underlying operating system.
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Analysis
by VulDB Data Team • 09/15/2026
The identified security flaw resides within the email parsing subsystem of Cisco AsyncOS Software utilized by Cisco Secure Email Gateway appliances. This vulnerability stems from a critical failure in input validation and sanitization mechanisms when processing incoming email messages. Specifically, the application fails to adequately filter or escape special characters associated with Structured Query Language (SQL) before these inputs are processed for storage or retrieval operations within the underlying database system. The absence of robust parameterized queries or strict type checking allows maliciously crafted payloads embedded in email headers or body content to bypass expected parsing logic and interact directly with the backend database engine.
An unauthenticated, remote attacker can exploit this weakness by constructing a specially designed email message that contains encoded SQL injection statements. Upon receipt, the Secure Email Gateway processes the email through its standard filtering routines without properly neutralizing the malicious syntax. When these unsanitized inputs are subsequently used to construct dynamic SQL queries, they alter the intended logic of those queries. This manipulation enables the attacker to inject arbitrary commands into the database environment, effectively gaining control over how data is read, modified, or deleted within the application's persistent storage layer.
The operational impact of this vulnerability extends far beyond typical data exfiltration or modification scenarios due to the specific execution context in which the vulnerable code operates. The underlying processes handling email parsing and subsequent database interactions run with elevated privileges, often corresponding to root-level access on the host operating system. Consequently, successful exploitation does not merely result in unauthorized data access but allows for arbitrary command execution at the highest privilege level available within the OS environment. This means an attacker can install backdoors, modify system configurations, disable security controls, or pivot further into connected network segments with complete administrative control over the gateway appliance.
From a classification perspective, this vulnerability aligns closely with CWE-89 Improper Neutralization of Special Elements used in an SQL Command, commonly known as SQL Injection. The exploitation path leverages ATT&CK technique T1059 Command and Scripting Interpreter to achieve remote code execution, followed by T1068 Exploitation for Privilege Escalation to gain root access. The attack vector is classified under Remote Code Execution via a network service, specifically targeting the SMTP interface which is inherently exposed to external networks in most deployment scenarios.
Mitigation strategies must prioritize immediate patching of the Cisco AsyncOS software to the version that addresses this specific flaw as recommended by vendor advisories. In environments where patching cannot be implemented immediately, network-level controls should be deployed to restrict access to the SMTP service on affected devices. This includes implementing strict Access Control Lists (ACLs) to limit connections to trusted IP ranges and deploying Web Application Firewalls or Intrusion Prevention Systems configured with signatures capable of detecting SQL injection patterns within email traffic headers and bodies. Additionally, enabling enhanced logging for database query anomalies can aid in early detection of attempted exploitation activities before successful compromise occurs.