XWiki Platform allows remote code execution from user account

Impact

When an admin disables a user account, the user's profile is executed with the admin's rights. This allows a user to place malicious code in the user profile before getting an admin to disable the user account.

To reproduce, as a user without script nor programming rights, edit the about section of your user profile and add {{groovy}}services.logging.getLogger("attacker").error("Hello from Groovy!"){{/groovy}}.
As an admin, go to the user profile and click the "Disable this account" button.
Then, reload the page. If the logs show attacker - Hello from Groovy! then the instance is vulnerable.

Patches

This has been patched in XWiki 14.10.21, 15.5.5, 15.10.6 and 16.0.0.

Workarounds

We're not aware of any workaround except upgrading.

References

• https://jira.xwiki.org/browse/XWIKI-21611
• https://github.com/xwiki/xwiki-platform/commit/f89c8f47fad6e5cc7e68c69a7e0acde07f5eed5a