| Package | Affected versions | Patched versions |
|---|---|---|
| org.xwiki.commons:xwiki-commons-xml | ≥ 4.2-milestone-1, < 14.6-rc-1 | 14.6-rc-1 |
| xwiki | ≥ 5.0, ≤ 14.5 |
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). An example are anonymous comments in XWiki where the HTML macro filters HTML using restricted mode:
{{html}}
<a href='' onclick='alert(1)'>XSS</a>
{{/html}}
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.
If you have any questions or comments about this advisory:
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