serendipity_event_freetag: Plugin update, XSS bug

Thanks to Stefan Schurtz, who reported a XSS issue in the serendipity_event_freetag plugin (SSCHADV2011-004). The issue was fixed in version 3.22 of the plugin, you can fetch the update through Spartacus or download via Spartacus.s9y.org.

The bug was introduced in version 3.20 of the plugin. Users of the plugin should upgrade, as it allows malicious users to trick people into visiting a specially crafted link on your blog to steal cookie login information for example, if you click on such a link.