Nextcloud Server before 9.0.54 and 10.0.0 suffers from an improper authorization check on removing shares. The Sharing Backend as implemented in Nextcloud does differentiate between shares to users and groups. In case of a received group share, users should be able to unshare the file to themselves but not to the whole group. The previous API implementation simply unshared the file to all users in the group.
The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action.
| Link | Tags |
|---|---|
| https://github.com/nextcloud/server/commit/7289cb5ec0b812992ab0dfb889744b94bc0994f0 | issue tracking third party advisory patch |
| https://github.com/nextcloud/server/commit/3387e5d00fcf6b2ea6b285a091e5743f545e7202 | issue tracking third party advisory patch |
| https://github.com/nextcloud/server/commit/a5471b4a3e3f30e99e4de39c97c0c3b3c2f1618f | issue tracking third party advisory patch |
| https://github.com/nextcloud/server/commit/e2c4f4f9aa11bc92e8f2212cce73841b922187e8 | issue tracking third party advisory patch |
| http://www.securityfocus.com/bid/97287 | vdb entry third party advisory |
| https://nextcloud.com/security/advisory/?id=nc-sa-2016-007 | patch vendor advisory |
| https://hackerone.com/reports/153905 | third party advisory exploit |