Part-DB is an open source inventory management system for electronic components. Prior to version 2.12.1, the part attachment upload handler stores uploaded files under the web-served media directory using the client-supplied file extension, and its extension blocklist does not include phar. AttachmentSubmitHandler::renameBlacklistedExtensions() rewrites dangerous extensions (php, phtml, sh, cgi, py, js, html, htaccess, ...) to .txt, but phar is absent from the list, so a .phar file keeps its extension. Public attachments (the default) are written into public/media/, which is the Apache document root.
The shipped Apache configuration routes .phar to PHP-FPM, so the stored file is executed as PHP on request. The per-attachment-type extension filter is empty by default and is not consulted by the upload handler in a way that blocks this, and a non-admin user in the default users group can create an attachment type with no filter and attach files to parts. Any authenticated user in the default users group uploads a .phar attachment to a part and fetches it under /media/, executing arbitrary PHP as the www-data web user.
Ability to exploit depends on the webserver config, docker image contained the vulnerability by default. This issue has been patched in version 2.12.1.
Attack Parameters
Impact Assessment
CVSS Vector v3.1