CVE-2025-66296: Grav vulnerable to Privilege Escalation in Grav Admin: Missing Username Uniqueness Check Allows Admin Account Takeover

A privilege escalation vulnerability exists in Grav’s Admin plugin due to the absence of username uniqueness validation when creating users. A user with the create user permission can create a new account using the same username as an existing administrator account, set a new password/email, and then log in as that administrator. This effectively allows privilege escalation from limited user-manager permissions to full administrator access.