Nextcloud Server before 12.0.8 and 13.0.3 suffers from improper checks of dropped permissions for incoming shares allowing a user to still request previews for files it should not have access to.
[
{
"product": "Nextcloud Server",
"vendor": "Nextcloud",
"versions": [
{
"status": "affected",
"version": "<13.0.3, <12.0.8"
}
]
}
]