Impact By either creating a new or editing an existing document with an icon set, an attacker can inject XWiki syntax and Velocity code that is executed with programming rights and thus allows remote code execution. There are different attack vectors, the simplest is the Velocity code in the icon set's HTML or XWiki syntax definition. The icon picker can be used to trigger the rendering of any icon set. The XWiki syntax variant of the icon set is also used without any escaping in some documents, allowing to inject XWiki syntax including script macros into a document that might have programming right, for this the currently used icon theme needs to be edited. Further, the HTML output of the icon set is output as JSON in the icon picker and this JSON is interpreted as XWiki syntax, allowing again the injection of script macros into a document with programming right and thus allowing remote code execution. This impacts the confidentiality, integrity and availability of the whole XWiki instance.
Patches
This has been patched in XWiki 14.10.6 and 15.1. Icon themes now require script right and the code in the icon theme is executed within the context of the icon theme, preventing any rights escalation. A macro for displaying icons has been introduced to avoid injecting the raw wiki syntax of an icon set into another document.
Workarounds There are no workarounds apart from upgrading to a version containing the fix.
References
https://jira.xwiki.org/browse/XWIKI-20524 https://github.com/xwiki/xwiki-platform/commit/b0cdfd893912baaa053d106a92e39fa1858843c7 https://github.com/xwiki/xwiki-platform/commit/46b542854978e9caa687a5c2b8817b8b17877d94 https://github.com/xwiki/xwiki-platform/commit/79418dd92ca11941b46987ef881bf50424898ff4
Impact Users are able to forge an URL with a payload allowing to inject Javascript in the page (XSS). It's possible to exploit the previewactions template to perform a XSS, e.g. by using URL such as: <hostname>/xwiki/bin/get/FlamingoThemes/Cerulean?xpage=xpart&vm=previewactions.vm&xcontinue=javascript:alert(document.domain)
This vulnerability exists since XWiki 6.1-rc-1.
Patches
The vulnerability has been patched in XWiki 14.10.5 and 15.1-rc-1.
Workarounds
It's possible to workaround the vulnerability by editing the template previewactions.vm to perform checks on it, but note that the appropriate fix involves new APIs that have been recently introduced in XWiki. See the referenced jira tickets.
References
Jira ticket about the vulnerability: https://jira.xwiki.org/browse/XWIKI-20342 Introduction of the macro used for fixing this type of vulnerability: https://jira.xwiki.org/browse/XWIKI-20583 Commit containing the actual fix in the template: https://github.com/xwiki/xwiki-platform/commit/9f01166b1a8ee9639666099eb5040302df067e4d
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
Attribution
This vulnerability has been reported by René de Sain @renniepak.
Impact A reflected XSS vulnerability in XWiki allows an attacker to send a victim to a URL with a deletion confirmation message on which the attacker-supplied script is executed when the victim clicks the "No" button. When the victim has admin or programming right, this allows the attacker to execute basically arbitrary actions on the XWiki installation including remote code execution.
Patches This vulnerability has been patched in XWiki 16.10.10, 17.4.2 and 17.5.0 by using the affected URL parameter only in the intended context.
Workarounds The patch can be manually applied to the templates that are present in the WAR. A restart of XWiki is needed for the changes to be applied.