Fix Logic Flow Bypass in Quarkus
Logic flow bypasses in Quarkus typically manifest when developers rely on implicit state or client-side flags to govern business transitions. In reactive architectures using Mutiny, failing to enforce strict state-machine transitions allows attackers to skip critical steps—like payment verification or MFA—by hitting downstream REST endpoints directly. To secure these, you must implement server-side state verification and ensure security contexts are propagated through the Uni/Multi chain.
The Vulnerable Pattern
@Path("/checkout") @Authenticated public class CheckoutResource {@POST @Path("/apply-discount") public void applyDiscount(@QueryParam("code") String code) { // Logic to apply discount } @POST @Path("/ship") public Response shipOrder(@QueryParam("orderId") Long orderId) { // VULNERABLE: Directly transitions to shipping without verifying // if the payment step was actually completed. Order order = Order.findById(orderId); order.status = "SHIPPED"; return Response.ok(order).build(); }
}
The Secure Implementation
The vulnerable code assumes that because the user reached the '/ship' endpoint, they must have completed the previous steps. An attacker can skip the payment process by POSTing directly to '/ship'. The secure implementation uses a 'Guard and Transition' pattern: it fetches the entity within a transaction, explicitly validates that the current state ('PAID') permits the requested transition ('SHIPPED'), and uses Mutiny's reactive chain to ensure the check is non-blocking yet mandatory before persistence.
@Path("/checkout") @Authenticated public class CheckoutResource {@Inject OrderRepository repository; @POST @Path("/ship") @Transactional public Uni<Response> shipOrder(@QueryParam("orderId") Long orderId) { return repository.findById(orderId) .onItem().ifNull().failWith(new NotFoundException("Order not found")) .invoke(order -> { // SECURE: Enforce state-machine integrity if (!"PAID".equals(order.status)) { throw new ForbiddenException("Logic bypass detected: Order status must be PAID to ship"); } }) .chain(order -> { order.status = "SHIPPED"; return repository.persistAndFlush(order); }) .map(order -> Response.ok(order).build()); }
}
Your Quarkus API
might be exposed to Logic Flow Bypass
74% of Quarkus apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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