CMSimple Remote Code Execution Vulnerability

A remote code execution vulnerability has been identified in CMSimple version 5.15. This vulnerability allows authenticated attackers to modify file extension settings and upload malicious PHP files. By appending ',php' to the Extensions_userfiles field, attackers can upload a shell script to the media directory, which is then executed on the server.

Impact

Exploitation of this vulnerability allows for arbitrary code execution on the server where CMSimple 5.15 is installed.

Reproduction

To reproduce this vulnerability, log into CMSimple 5.15 and navigate to the Settings > CMS section. Append ',php' to the Extensions_userfiles field and save the changes. Then, go to the Files > Media section and upload a PHP file, such as a shell script. Once uploaded, the shell can be accessed via the media directory.