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.