Incorrect username validation in the registration process of CTFd v2.0.0 - v2.2.2 allows an attacker to take over an arbitrary account if the username is known and emails are enabled on the CTFd instance. To exploit the vulnerability, one must register with a username identical to the victim's username, but with white space inserted before and/or after the username. This will register the account with the same username as the victim. After initiating a password reset for the new account, CTFd will reset the victim's account password due to the username collision.

An issue in the validateemail function in CTFd/utils/validators/init.py of CTFd 3.7.3 allows attackers to cause a Regular expression Denial of Service (ReDoS) via supplying a crafted string as e-mail address during registration.

A zip slip vulnerability in the Admin import functionality of CTFd v3.8.1-18-gdb5a18c4 allows attackers to write arbitrary files outside the intended directories via supplying a crafted import.

A vulnerability has been found in CTFd up to 3.8.4. The affected element is the function issafeurl of the file CTFd/utils/validators/init.py. Such manipulation of the argument Next leads to open redirect. The attack can be launched remotely. The exploit has been disclosed to the public and may be used. The name of the patch is 5d8515842fd1ab2c3a9f2dde9ffca907aa334ea9. Upgrading the affected component is recommended.