Plane is an open-source project management tool. Prior to 1.4.0, ProjectJoinEndpoint at GET /api/workspaces/{slug}/projects/{project_id}/join/{pk}/ uses permission_classes = [AllowAny] and returns the full ProjectMemberInvite record, including its email, token, and role, to unauthenticated callers. The corresponding POST endpoint checks only whether the submitted email matches project_invite.email and does not validate the invitation token. An attacker who knows the invitation UUID can discover