ownCloud Guests before 0.12.5 allows unauthenticated user enumeration via the /apps/guests/register/{email}/{token} endpoint. Because of insufficient validation of the supplied token in showPasswordForm, the server responds differently when an e-mail address corresponds to a valid pending guest user rather than a non-existent user.

Nextcloud guests app is a utility to create guest users which can only see files shared with them. In affected versions users were able to load the first page of apps they were actually not allowed to access. Depending on the selection of apps installed this may present a permissions bypass. It is recommended that the Guests app is upgraded to 2.4.1, 2.5.1 or 3.0.1. There are no known workarounds for this vulnerability.

Nextcloud guests app is a utility to create guest users which can only see files shared with them. In affected versions users could change the allowed list of apps, allowing them to use apps that were not intended to be used. It is recommended that the Guests app is upgraded to 2.4.1, 2.5.1 or 3.0.1. There are no known workarounds for this vulnerability.