A Missing Release of Memory after Effective Lifetime vulnerability in the Juniper Networks Junos OS on MX Series platforms with MPC10/MPC11 line cards, allows an unauthenticated adjacent attacker to cause a Denial of Service (DoS). Devices are only vulnerable when the Suspicious Control Flow Detection (scfd) feature is enabled. Upon enabling this specific feature, an attacker sending specific traffic is causing memory to be allocated dynamically and it is not freed. Memory is not freed even after deactivating this feature. Sustained processing of such traffic will eventually lead to an out of memory condition that prevents all services from continuing to function, and requires a manual restart to recover. The FPC memory usage can be monitored using the CLI command "show chassis fpc". On running the above command, the memory of AftDdosScfdFlow can be observed to detect the memory leak. This issue affects Juniper Networks Junos OS on MX Series: All versions prior to 20.2R3-S5; 20.3 version 20.3R1 and later versions.