An exploitable timing discrepancy vulnerability exists in the authentication functionality of the Web-Based Management (WBM) web application on WAGO PFC100/200 controllers. The WBM application makes use of the PHP crypt() function which can be exploited to disclose hashed user credentials. This affects WAGO PFC200 Firmware version 03.00.39(12) and version 03.01.07(13), and WAGO PFC100 Firmware version 03.00.39(12).