Arbitrary user password reset leading to administrator account takeover

The vulnerability allows any authenticated user to change their own password without providing the current password or having an active elevated session. It also allows the attacker to change other users’ passwords if the attacker’s account has edit users permission (which doesn’t allow changing others’ passwords) and lacks Administrate users permission (which is required to change others’ passwords).

The vulnerability exists in the elements/save action when saving a User element. The UserPasswordValidator applies only a safe validator to the newPassword field without an on scenario restriction. This makes newPassword mass-assignable during the generic element save flow, completely bypassing the dedicated users/set-password action that enforces elevated session verification.

An attacker with any authenticated session (whether it’s hijacked or a normal / low-privileged user) can change their own password, and potentially take over administrator accounts.

Required Permissions

• Access the control panel
• Edit users (needed for the account takeover attack scenario)

Impact

• Any authenticated user can change their own password without providing their current password.
• Users with Edit users permission can change any user’s password, including administrators.