CVE-2026-27602 in Modoboa
Summary
by MITRE • 03/25/2026
Modoboa is a mail hosting and management platform. Prior to version 2.7.1, `exec_cmd()` in `modoboa/lib/sysutils.py` always runs subprocess calls with `shell=True`. Since domain names flow directly into shell command strings without any sanitization, a Reseller or SuperAdmin can include shell metacharacters in a domain name to run arbitrary OS commands on the server. Version 2.7.1 patches the issue.
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Analysis
by VulDB Data Team • 04/01/2026
The vulnerability identified as CVE-2026-27602 affects Modoboa, a comprehensive mail hosting and management platform that serves as a centralized solution for email administration. This security flaw exists in versions prior to 2.7.1 and represents a critical command injection vulnerability that directly impacts the platform's security posture. The vulnerability stems from improper handling of user-supplied input within the system's command execution mechanisms, creating a pathway for privilege escalation and arbitrary code execution. The issue specifically resides in the `exec_cmd()` function located within the `modoboa/lib/sysutils.py` file, which demonstrates poor input validation practices that have severe operational implications for organizations relying on this platform.
The technical flaw manifests through the improper use of `shell=True` parameter in subprocess calls within the `exec_cmd()` function. This parameter enables shell interpretation of command strings, which creates an inherent risk when user input flows directly into shell commands without proper sanitization or escaping mechanisms. Domain names, which are user-controllable inputs in the mail hosting context, can contain shell metacharacters such as semicolons, ampersands, backticks, or pipes that when processed through the vulnerable function, get interpreted by the underlying shell rather than treated as literal string values. This design flaw allows an attacker to inject malicious commands that execute with the privileges of the Modoboa service account, potentially leading to complete system compromise.
The operational impact of this vulnerability is particularly severe given the roles that can exploit it. Resellers and SuperAdmins possess elevated privileges within the Modoboa platform and can manipulate domain names through the administrative interface. When these users create or modify domain entries containing malicious shell metacharacters, the system executes these commands with the same privileges as the Modoboa service, which typically runs with system-level access. This scenario enables attackers to perform unauthorized actions such as data exfiltration, system reconnaissance, privilege escalation, or even complete system compromise. The vulnerability essentially provides a direct path to arbitrary command execution that bypasses normal authentication and authorization mechanisms, making it particularly dangerous in multi-tenant environments where different users manage separate domains.
This vulnerability aligns with CWE-78, which specifically addresses "Improper Neutralization of Special Elements used in OS Command" and represents a classic command injection attack vector. The flaw also connects to ATT&CK technique T1059.001, "Command and Scripting Interpreter: PowerShell", although the actual attack vector here involves shell command execution rather than PowerShell specifically. Organizations using Modoboa should immediately implement the patch released in version 2.7.1, which addresses the core issue by eliminating the `shell=True` parameter usage and implementing proper input sanitization. The mitigation strategy should also include monitoring for suspicious domain name creations and implementing network-level controls to prevent unauthorized access to the Modoboa administrative interface. Additionally, organizations should conduct thorough security reviews of other system components that might exhibit similar patterns of unsafe command execution, ensuring that all user-supplied inputs are properly validated and sanitized before being processed in shell contexts.