New services are designed for the future of Internet, and some of them will require the network to provide low latency traffic. Many optimizations targeting latency reduction have been proposed. Among them, re-architecting congestion control and active queue management (AQM) has been particularly studied. L4S [1,2,3] (Low Latency, Low Loss and Scalable Throughput) is a new network architecture that aims at allowing coexistence between low latency traffic and classic traffic within a single node, involving a dual queue coupled AQM. Although this architecture sounds promising for latency improvement, an attacker can exploit some vulnerabilities to defeat its low-latency features and consequently make some services unusable. In addition, we prove that application-layer protocols such as QUIC can easily be hacked in order to exploit the over sensitivity of those new services to network variations. By implementing undesirable flows in a testbed and evaluating how they impact the delivery of low-latency flows, we demonstrate their reality and the need of research in the detection of this new kind of threats [4,5].