XWiki Platform Web Templates vulnerable to Unauthorized User Registration Through the Distribution Wizard

Vulnerability Description

XWiki Platform Web Templates are templates for XWiki Platform, a generic wiki platform. By passing a template of the distribution wizard to the xpart template, user accounts can be created even when user registration is disabled. This also circumvents any email verification. Before versions 14.2 and 13.10.4, this can also be exploited on a private wiki, thus potentially giving the attacker access to the wiki. Depending on the configured default rights of users, this could also give attackers write access to an otherwise read-only public wiki. Users can also be created when an external authentication system like LDAP is configured, but authentication fails unless the authentication system supports a bypass/local accounts are enabled in addition to the external authentication system. This issue has been patched in XWiki 13.10.5 and 14.3RC1. As a workaround, one may replace `xpart.vm`, the entry point for this attack, by a patched version from the patch without updating XWiki.

References

• https://github.com/xwiki/xwiki-platform/security/advisories/GHSA-h5j3-5x63-p8jv
• https://github.com/xwiki/xwiki-platform/commit/70c64c23f4404f33289458df2a08f7c4be022755
• https://jira.xwiki.org/browse/XWIKI-19558