In RedpwnCTF before version 2.3, there is a session fixation vulnerability in exploitable through the "#token=$ssid" hash when making a request to the "/verify" endpoint. An attacker team could potentially steal flags by, for example, exploiting a stored XSS payload in a CTF challenge so that victim teams who solve the challenge are unknowingly (and against their will) signed into the attacker team's account. Then, the attacker can gain points / value off the backs of the victims. This is patched in version 2.3.