Unescaped passing of the request URL in Collabora Online

Collabora Online is a collaborative online office suite based on LibreOffice technology. Users of Nextcloud with Collabora Online Built-in CODE Server app can be vulnerable to attack via proxy.php. This vulnerability has been fixed in Collabora Online - Built-in CODE Server (richdocumentscode) release 23.5.403. Users are advised to upgrade. There are no known workarounds for this vulnerability.