Eval injection vulnerability in the configure script in TWiki 4.0.0 through 4.0.4 allows remote attackers to execute arbitrary Perl code via an HTTP POST request containing a parameter name starting with "TYPEOF".
The history (revision control) function in TWiki 02-Sep-2004 and earlier allows remote attackers to execute arbitrary code via shell metacharacters, as demonstrated via the rev parameter to TWikiUsers.
TWiki allows arbitrary shell command execution via the Include function
The ImageGalleryPlugin (ImageGalleryPlugin.pm) in Twiki allows remote attackers to execute arbitrary commands via certain commands that generate thumbnails.