Deleting users with certain names caused system files to be deleted. Risk is higher for systems which allow users to register themselves and have the data directory in the web root. This affects ownCloud/core versions < 10.6.
ownCloud Server before 8.2.12, 9.0.x before 9.0.10, 9.1.x before 9.1.6, and 10.0.x before 10.0.2 are vulnerable to XSS on error pages by injecting code in url parameters.
Inadequate escaping lead to XSS vulnerability in the search module in ownCloud Server before 8.2.12, 9.0.x before 9.0.10, 9.1.x before 9.1.6, and 10.0.x before 10.0.2. To be exploitable a user has to write or paste malicious content into the search dialogue.
A logical error in ownCloud Server before 10.0.2 caused disclosure of valid share tokens for public calendars. Thus granting an attacker potentially access to publicly shared calendars without knowing the share token.