19th July 2016
Risk level: Low
CVSS v3 Base Score: 3.1 (AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N)
CWE: Permission Issues (CWE-275)
HackerOne report: 146067
The restore capability of Nextcloud was not verifying whether an user has only read-only access to a share. Thus an user with read-only access was able to restore old versions.
The permission check is now also performed on restore actions.
It is recommended that all instances are upgraded to Nextcloud 9.0.52.
The Nextcloud team thanks the following people for their research and responsible disclosure of the above advisory: