ToolJet from 3.20.2-lts before 3.20.242-lts contains an authorization bypass in SignupDisableGuard, which treats the string signup setting 'false' as truthy, so instance-level signup restrictions are not enforced. Unauthenticated attackers can send POST requests to /api/signup without an organizationId to create an account, join the default workspace, and receive a valid session.