Files Drop public link can be added as federated share

Description

Impact

An attacker is able to convert a Files Drop link to a federated share. This causes an issue on the UI side of the sharing user. When the sharing user opens the sharing panel and tries to remove the “Create” privileges of this unexpected share, Nextcloud server would silently grant the share read privileges.

Patches

It is recommended that the Nextcloud Server is upgraded to 19.0.11, 20.0.10 or 21.0.2.

Workarounds

None.

References

• HackerOne

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