Index: t3lib/class.t3lib_div.php
===================================================================
--- t3lib/class.t3lib_div.php	(Revision 6510)
+++ t3lib/class.t3lib_div.php	(Arbeitskopie)
@@ -4120,7 +4120,7 @@
 			);
 
 				// Pass if URL is on the current host:
-			if (self::isValidUrl($decodedUrl)) {
+			if (self::isValidUrl($decodedUrl) && preg_match('#^[a-z0-9]+://#', $decodedUrl)) {
 				if (self::isOnCurrentHost($decodedUrl) && strpos($decodedUrl, self::getIndpEnv('TYPO3_SITE_URL')) === 0) {
 					$sanitizedUrl = $url;
 				}