Index: t3lib/class.t3lib_userauth.php
===================================================================
--- t3lib/class.t3lib_userauth.php	(Revision 8748)
+++ t3lib/class.t3lib_userauth.php	(Arbeitskopie)
@@ -157,6 +157,7 @@
 
 		// Internals
 	var $id;							// Internal: Will contain session_id (MD5-hash)
+	protected $idHash;					// Internal: MD5 hash of the session id, used in combination with veriCode (vC)
 	var $cookieId;						// Internal: Will contain the session_id gotten from cookie or GET method. This is used in statistics as a reliable cookie (one which is known to come from $_COOKIE).
 	var $loginFailure = FALSE;			// Indicates if an authentication was started but failed
 	var $loginSessionStarted = FALSE;	// Will be set to true if the login session is actually written during auth-check.
@@ -774,6 +775,10 @@
 		$dbres = $this->fetchUserSessionFromDB();
 
 		if ($dbres && $user = $GLOBALS['TYPO3_DB']->sql_fetch_assoc($dbres)) {
+			if (!$this->id) {
+				$this->id = $user['ses_id'];
+			}
+
 				// A user was found
 			if (is_string($this->auth_timeout_field))	{
 				$timeout = intval($user[$this->auth_timeout_field]);		// Get timeout-time from usertable
@@ -893,7 +898,7 @@
 				$dbres = $GLOBALS['TYPO3_DB']->exec_SELECTquery(
 						'*',
 						$this->session_table.','.$this->user_table,
-						$this->session_table.'.ses_id = '.$GLOBALS['TYPO3_DB']->fullQuoteStr($this->id, $this->session_table).'
+						'MD5(' . $this->session_table.'.ses_id) = '.$GLOBALS['TYPO3_DB']->fullQuoteStr($this->getIdHash(), $this->session_table).'
 							AND '.$this->session_table.'.ses_name = '.$GLOBALS['TYPO3_DB']->fullQuoteStr($this->name, $this->session_table).'
 							AND '.$this->session_table.'.ses_userid = '.$this->user_table.'.'.$this->userid_column.'
 							'.$this->ipLockClause().'
@@ -978,10 +983,24 @@
 	 * @return	string
 	 */
 	public function veriCode() {
-		return substr(md5($this->id . $GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey']), 0, 10);
+		return substr(md5($this->getIdHash() . $GLOBALS['TYPO3_CONF_VARS']['SYS']['encryptionKey']), 0, 10);
 	}
 
 	/**
+	 * Gets the current idHash.
+	 *
+	 * @return string
+	 */
+	public function getIdHash() {
+		if (!isset($this->idHash)) {
+			$idHash = t3lib_div::_GP('idHash');
+			$this->idHash = ($idHash ? $idHash : md5($this->id));
+		}
+
+		return $this->idHash;
+	}
+
+	/**
 	 * This returns the where-clause needed to lock a user to a hash integer
 	 *
 	 * @return	string
Index: typo3/js/flashupload.js
===================================================================
--- typo3/js/flashupload.js	(Revision 8748)
+++ typo3/js/flashupload.js	(Arbeitskopie)
@@ -280,6 +280,7 @@
 			swfConfig.post_params            = Ext.value(this.uploadPostParams, this.swfDefaultConfig.post_params);
 			// add the veriCode from the backend.php to verify the session with the flash client
 			swfConfig.post_params.vC         = top.TS.veriCode;
+			swfConfig.post_params.idHash     = top.TS.idHash;
 			swfConfig.file_types_description = Ext.value(this.uploadFileTypesDescription, this.swfDefaultConfig.file_types_description);
 			this.setFileTypeRestrictions(this.uploadFileTypes);
 			return swfConfig;
Index: typo3/backend.php
===================================================================
--- typo3/backend.php	(Revision 8748)
+++ typo3/backend.php	(Arbeitskopie)
@@ -386,6 +386,7 @@
 			'inWorkspace' => $GLOBALS['BE_USER']->workspace !== 0 ? 1 : 0,
 			'workspaceFrontendPreviewEnabled' => $GLOBALS['BE_USER']->user['workspace_preview'] ? 1 : 0,
 			'veriCode' => $GLOBALS['BE_USER']->veriCode(),
+			'idHash' => $GLOBALS['BE_USER']->getIdHash(),
 			'denyFileTypes' => PHP_EXTENSIONS_DEFAULT,
 			'moduleMenuWidth' => $this->menuWidth - 1,
 			'topBarHeight' => (isset($GLOBALS['TBE_STYLES']['dims']['topFrameH']) ? intval($GLOBALS['TBE_STYLES']['dims']['topFrameH']) : 30),
@@ -477,6 +478,7 @@
 		this.navFrameWidth = 0;
 		this.securityLevel = TYPO3.configuration.securityLevel;
 		this.veriCode = TYPO3.configuration.veriCode;
+		this.idHash = TYPO3.configuration.idHash;
 		this.denyFileTypes = TYPO3.configuration.denyFileTypes;
 	}
 	var TS = new typoSetup();