XWiki Platform Old Core: Resource path traversal via /skin/ action endpoint in Jetty 12+

Impact

With Jetty 12+ a user can craft a URL to access any resource the Jetty instance is allowed to access.

For example http://[host]/xwiki/bin/skin/..%252f/..%252f..%252f..%252f..%252f..%252f..%252f..%252fetc/passwd allows downloading the content of the /etc/passwd file, provided Jetty is allowed to read it, and if your XWiki webapp is located exactly 5 levels below / (like /var/lib/jetty/webapps/xwiki, which is the case in the docker image, for example).

Another example which does not go out of the XWiki webapp, but it's still a vulnerability (since users should not be allowed to access Hibernate or XWiki configuration files) is http://[host]/xwiki/bin/skin/..%252f/..%252fWEB-INF/xwiki.cfg.

Patches

This vulnerability has been patched in XWiki 17.10.5 and 18.2.0.

Workarounds

A possible workaround is to use a different application server, like Jetty < 12 (in the case of XWiki < 17) or Tomcat, which don't seem to be impacted.

Resources

• https://jira.xwiki.org/browse/XWIKI-24075
• https://jira.xwiki.org/browse/XCOMMONS-3594

For more information

If there are any questions or comments about this advisory:

• Open an issue in Jira XWiki.org
• Send an email to the Security Mailing List

Attribution

Lê Ngọc Khoa reported the vulnerability.