XWiki Commons are technical libraries common to several other top level XWiki projects. There was no check in the author of a JavaScript xobject or StyleSheet xobject added in a XWiki document, so until now it was possible for a user having only Edit Right to create such object and to craft a script allowing to perform some operations when executing by a user with appropriate rights. This has been patched in XWiki 14.9-rc-1 by only executing the script if the author of it has Script rights.
Impact An attacker can create a template provider on any document that is part of the wiki (could be the attacker's user profile) that contains malicious code. This code is executed when this template provider is selected during document creation which can be triggered by sending the user to a URL. For the attacker, the only requirement is to have an account as by default the own user profile is editable. This allows an attacker to execute arbitrary actions with the rights of the user opening the malicious link. Depending on the rights of the user, this may allow remote code execution and full read and write access to the whole XWiki installation.
For reproduction, the following steps can be used: 1. As a simple user with no script right, edit the user profile with the object editor and add an object of type "Template Provider Class". Set the name to "My Template", set template to any page on the wiki. In "Creation Restrictions", enter <img onerror="alert(1)" src="https://www.example.com". Accept the suggestion to add this string in the dropdown. Click "Save & View" 2. As any user with edit right, open <xwiki-host>/xwiki/bin/create/Main/WebHome?parent=&templateprovider=XWiki.<username>&name=foo&spaceReference=Bar, where <xwiki-host> is the URL of your XWiki installation and <username> is the username of the attacker.
If an alert is displayed, the installation is vulnerable.
Patches This has been patched in XWiki 14.10.12 and 15.5RC1 by adding the appropriate escaping.
Workarounds The vulnerable template file createinline.vm is part of XWiki's WAR and can be patched by manually applying the changes from the fix.
References https://github.com/xwiki/xwiki-platform/commit/ba56fda175156dd35035f2b8c86cbd8ef1f90c2e https://jira.xwiki.org/browse/XWIKI-20962
Impact A user without Script or Programming right is able to execute script requiring privileges by editing gadget titles in the dashboard.
Patches The issue has been patched in XWiki 12.6.7, 12.10.3 and 13.0RC1.
Workarounds There's no easy workaround for this issue, it is recommended to upgrade XWiki.
References https://jira.xwiki.org/browse/XWIKI-17794
For more information If you have any questions or comments about this advisory: Open an issue in JIRA Email us at XWiki security mailing-list