We've been reported (thanks to jakovits) a cross site scripting vulnerability in 4images 1.7 - 1.7.11.
To fix this:
In global.php
find
$string = preg_replace('#</*(applet|meta|xml|blink|link|style|script|embed|object|iframe|frame|frameset|ilayer|layer|bgsound|title|base)[^>]*>#i',"",$string);
and replace it with
$string = preg_replace('#</*(applet|meta|xml|blink|link|style|script|embed|object|iframe|frame|frameset|ilayer|layer|bgsound|title|base)[^>]*(>|$)#i',"",$string);