Unspecified vulnerability in the subscriptions manager in Invision Power Board (IPB or IP.Board) 2.3.1 before 20070912 allows remote authenticated users to change the member ID and reduce the privilege level of arbitrary users via a crafted payment form, related to (1) class_gw_2checkout.php, (2) class_gw_authorizenet.php, (3) class_gw_nochex.php, (4) class_gw_paypal.php, and (5) class_gw_safshop.php in sources/classes/paymentgateways/.