A NULL Pointer Dereference vulnerability in the flow daemon (flowd) of Juniper Networks Junos OS on SRX Series allows an attacker causing specific, valid control traffic to be sent out of a Dual-Stack (DS) Lite tunnel to crash the flowd process, resulting in a Denial of Service (DoS).  Continuous triggering of specific control traffic will create a sustained Denial of Service (DoS) condition. On all SRX platforms, when specific, valid control traffic needs to be sent out of a DS-Lite tunnel, a segmentation fault occurs within the flowd process, resulting in a network outage until the flowd process restarts. This issue affects Junos OS on SRX Series: * All versions before 21.2R3-S9, * from 21.4 before 21.4R3-S9, * from 22.2 before 22.2R3-S5, * from 22.4 before 22.4R3-S6, * from 23.2 before 23.2R2-S3, * from 23.4 before 23.4R2.