rtehtmlarea/pi1/class.tx_rtehtmlarea_pi1.php in Typo3 4.0.0 through 4.0.3, 3.7 and 3.8 with the rtehtmlarea extension, and 4.1 beta allows remote authenticated users to execute arbitrary commands via shell metacharacters in the userUid parameter to rtehtmlarea/htmlarea/plugins/SpellChecker/spell-check-logic.php, and possibly another vector.
http://www.vupen.com/english/advisories/2006/5094
http://www.securityfocus.com/archive/1/454944/100/0/threaded
http://typo3.org/news-single-view/?tx_newsimporter_pi1%5BshowItem%5D=0&cHash=e4a40a11a9
http://securityreason.com/securityalert/2056
http://secunia.com/advisories/23466
http://secunia.com/advisories/23446
http://lists.netfielders.de/pipermail/typo3-announce/2006/000046.html
http://lists.netfielders.de/pipermail/typo3-announce/2006/000045.html