ZoneMinder is a free, open source closed-circuit television software application. Prior to 1.38.3, downloadEvents() manually wraps a monitor Name value in single quotes instead of using escapeshellarg() before placing it in shell commands when a user with monitor-create or monitor-edit permission stores a monitor Name containing shell metacharacters and a user with Events View permission exports that monitor's events. In this attack mechanism, the stored monitor Name reaches both the ffmpeg concatenation command and the tar or zip archive command and breaks out of manual quoting. Arbitrary commands execute as the web server user. This issue is fixed in version 1.38.3.