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.