Impact XWiki's REST API doesn't enforce any limits for the number of items that can be requested in a single request at the moment. Depending on the number of pages in the wiki and the memory configuration, this can lead to slowness and unavailability of the wiki. As an example, the /rest/wikis/xwiki/spaces resource returns all spaces on the wiki by default, which are basically all pages.

Patches XWiki 17.7.0RC1, 17.4.4 and 16.10.11 introduce a configurable limit, limiting responses to 1000 items by default. Requesting larger limits leads to an error now.

Workarounds We're not aware of any workaround, except denying access to the affected REST resources in a proxy in front of XWiki.

Impact A reflected cross site scripting (XSS) vulnerability in XWiki allows an attacker to execute arbitrary actions in XWiki with the rights of the victim if the attacker manages to trick a victim into visiting a crafted URL. If the victim has administrative or programming rights, those rights can be exploited to gain full access to the XWiki installation.

Patches This vulnerability has been patched in XWiki 17.8.0RC1, 17.4.5 and 16.10.12.

Workarounds The patch can be applied manually, only a single line in templates/loggingmacros.vm needs to be changed, no restart is required.

References https://github.com/xwiki/xwiki-platform/commit/8337ac8c3b19c37f306723b638b2cae8b0a57dbf https://jira.xwiki.org/browse/XWIKI-23462

Attribution

We thank Mike Cole @mikecole-mg for discovering and reporting this vulnerability.