Vodafone H500s devices running firmware v3.5.10 (hardware model Sercomm VFH500) expose the WiFi access point password via an unauthenticated HTTP endpoint. By sending a crafted GET request to /data/activation.json with specific headers and cookies, a remote attacker can retrieve a JSON document that contains the wifi_password field. This allows an unauthenticated attacker to obtain the WiFi credentials and gain unauthorized access to the wireless network, compromising confidentiality of network traffic and attached systems.