pagekit download server-side request forgery

A vulnerability was identified in pagekit up to 1.0.18. Affected by this issue is some unknown functionality of the file /index.php/admin/system/update/download. The manipulation of the argument url leads to server-side request forgery. Remote exploitation of the attack is possible. The exploit is publicly available and might be used. The vendor was contacted early about this disclosure but did not respond in any way.