The ImageGalleryPlugin (ImageGalleryPlugin.pm) in Twiki allows remote attackers to execute arbitrary commands via certain commands that generate thumbnails.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2005-0517
http://www.enyo.de/fw/security/notes/twiki-robustness.html
http://static.enyo.de/fw/patches/twiki/imagegallery-robustness-20041128.diff