--- class.t3lib_beuserauth.php	2011-12-19 12:02:46.501404721 +0100
+++ class.t3lib_beuserauth.php.new	2011-12-19 11:58:02.593871739 +0100
@@ -406,6 +406,12 @@
 			// Backend user is allowed if adminOnly is set to 2 (CLI) and a CLI process is running:
 		} elseif ($adminOnlyMode == 2 && (TYPO3_REQUESTTYPE & TYPO3_REQUESTTYPE_CLI)) {
 			$isUserAllowedToLogin = TRUE;
+		} elseif ($this->user['ses_backuserid']) {
+			$backUserId = intval($this->user['ses_backuserid']);
+			$res = $GLOBALS['TYPO3_DB']->exec_SELECTquery('*', 'be_users', 'uid='.$backUserId.' AND admin=1'.t3lib_BEfunc::BEenableFields('be_users'));
+			if ($GLOBALS['TYPO3_DB']->sql_fetch_row($res)) {
+				$isUserAllowedToLogin = TRUE;
+			}
 		}
 
 		return $isUserAllowedToLogin;