Impact
This vulnerability impacts users of a subwiki of XWiki where Message Stream is enabled and use, if they configured their wiki to be closed by selecting "Prevent unregistered users to view pages" in the Administrations Rights.
The vulnerability is that any message sent in a subwiki to "everyone" is actually sent to the farm: any visitor of the main wiki will be able to see that message through the Dashboard, even if the subwiki is configured to be private.
Patches
This problem has not been patched and is not going to be patched in the future: Message Stream has been deprecated in XWiki 16.8.0RC1 and is not maintained anymore.
Workarounds
Message Stream is disabled by default, it's advised to keep it disabled from Administration > Social > Message Stream.
References
https://jira.xwiki.org/browse/XWIKI-17154
XWiki Platform Security Parent POM contains the security APIs for XWiki Platform, a generic wiki platform. Starting with version 5.0 and prior to 12.10.11, 13.10.1, and 13.4.6, a bug in the security cache stores rules associated to document Page1.Page2 and space Page1.Page2 in the same cache entry. That means that it's possible to overwrite the rights of a space or a document by creating the page of the space with the same name and checking the right of the new one first so that they end up in the security cache and are used for the other too. The problem has been patched in XWiki 12.10.11, 13.10.1, and 13.4.6. There are no known workarounds.
XWiki Commons are technical libraries common to several other top level XWiki projects. The "restricted" mode of the HTML cleaner in XWiki, introduced in version 4.2-milestone-1, only escaped <script> and <style>-tags but neither attributes that can be used to inject scripts nor other dangerous HTML tags like <iframe>. As a consequence, any code relying on this "restricted" mode for security is vulnerable to JavaScript injection ("cross-site scripting"/XSS). When a privileged user with programming rights visits such a comment in XWiki, the malicious JavaScript code is executed in the context of the user session. This allows server-side code execution with programming rights, impacting the confidentiality, integrity and availability of the XWiki instance. This problem has been patched in XWiki 14.6 RC1 with the introduction of a filter with allowed HTML elements and attributes that is enabled in restricted mode. There are no known workarounds apart from upgrading to a version including the fix.
Impact
It is possible to access the hash of a password by using the diff feature of the history whenever the object storing the password is deleted. Using that vulnerability it's possible for an attacker to have access to the hash password of a user if they have rights to edit the users' page.
Now with the default right scheme in XWiki this vulnerability is normally prevented on user profiles, except by users with Admin rights. Note that this vulnerability also impacts any extensions that might use passwords stored in xobjects: for those usecases it depends on the right of those pages.
There is currently no way to be 100% sure that this vulnerability has been exploited, as an attacker with enough privilege could have deleted the revision where the xobject was deleted after rolling-back the deletion. But again, this operation requires high privileges on the target page (Admin right). A page with a user password xobject which have in its history a revision where the object has been deleted should be considered at risk and the password should be changed there.
Patches
The vulnerability has been patched in XWiki 14.10.19, 15.5.4 and 15.9-rc-1 by performing a better check before dislaying data of a diff, to ensure it's not coming from a password field.
Workarounds
Admins should ensure that the user pages are properly protected: the edit right shouldn't be allowed for other users than Admin and owner of the profile (which is the default right). Now there's not much workaround possible for a privileged user other than upgrading XWiki.
References
JIRA ticket: https://jira.xwiki.org/browse/XWIKI-19948 Commit: https://github.com/xwiki/xwiki-platform/commit/f1eaec1e512220fabd970d053c627e435a1652cf
For more information
If you have any questions or comments about this advisory: Open an issue in Jira XWiki.org Email us at Security Mailing List