Headline
CVE-2021-41241: Groupfolders advanced permissions is not obeyed for subfolders
Nextcloud server is a self hosted system designed to provide cloud style services. The groupfolders application for Nextcloud allows sharing a folder with a group of people. In addition, it allows setting “advanced permissions” on subfolders, for example, a user could be granted access to the groupfolder but not specific subfolders. Due to a lacking permission check in affected versions, a user could still access these subfolders by copying the groupfolder to another location. It is recommended that the Nextcloud Server is upgraded to 20.0.14, 21.0.6 or 22.2.1. Users unable to upgrade should disable the “groupfolders” application in the admin settings.
Impact
The groupfolders application for Nextcloud allows sharing a folder with a group of people. In addition, it allows setting “advanced permissions” on subfolders, for example, a user could be granted access to the groupfolder but not specific subfolders.
Due to a lacking permission check, a user could still access these subfolders by copying the groupfolder to another location.
Patches
It is recommended that the Nextcloud Server is upgraded to 20.0.14, 21.0.6 or 22.2.1.
Workarounds
Disable the “groupfolders” application in the admin settings.
References
- Bug Report
- Pull Request
For more information
If you have any questions or comments about this advisory:
- Create a post in nextcloud/security-advisories
- Customers: Open a support ticket at support.nextcloud.com
Related news
Gentoo Linux Security Advisory 202208-17 - Multiple vulnerabilities have been found in Nextcloud, the worst of which could result in denial of service. Versions less than 23.0.4 are affected.