A Command Injection vulnerability exists in Roundcube versions before 1.4.4, 1.3.11 and 1.2.10.
Because the "_im_convert_path" does not perform sanitization/input filtering, an attacker with access to the Roundcube Installer can inject system commands in this parameter that will execute when any user opens any email containing a "non-standard" image.
The vendor's disclosure and fix for this vulnerability can be found here.
This vulnerability requires:
- Access to the Roundcube Webmail installer component
- Waiting for a Roundcube user to open an email containg a non-standard image
More details and the exploitation process can be found in this PDF.