The "through the web code" capability for Zope 2.0 through 2.5.1 b1 allows untrusted users to shut down the Zope server via certain headers.
https://github.com/advisories/GHSA-vwrc-g9q6-f675
http://www.zope.org/Products/Zope/Hotfix_2002-04-15/security_alert
http://www.securityfocus.com/bid/5813