Hotfix 2002-04-15 (Server shutdown vulnerability)
This hotfix addresses an important security issue that may affect some users of Zope versions 2.0 through 2.5.1 b1.
The issue involves a vulnerability involving "through the web code" inadvertently allowing an untrusted user to remotely shut down a Zope server by allowing the user to inject special headers into the response. If you allow untrusted users to write "through the web" code like Python Scripts, DTML Methods, or Page Templates, your Zope server is vulnerable.
We highly recommend that any Zope site have this hotfix product installed to mitigate the issue. Zope 2.5.1b2 and 2.4.4b2 as well as subsequent Zope release versions will contain a fix for the issue, at which time the hotfix can be removed.
http://www.zope.org/Products/Zope/Hotfix_2002-04-15/Affects Zope 2.0 - 2.5.1/Hotfix_2002-04-15.tgz