CVE-2018-5264

Ubiquiti UniFi 52 devices, when Hotspot mode is used, allow remote attackers to bypass intended restrictions on “free time” Wi-Fi usage by sending a /guest/s/default/ request to obtain a cookie, and then using this cookie in a /guest/s/default/login request with the byfree parameter.
Source: NIST
CVE-2018-5264