In BIG-IP LTM, AAM, AFM, Analytics, APM, ASM, DNS, Link Controller, PEM, and WebSafe software 12.0.0 to 12.1.1, in some cases the Traffic Management Microkernel (TMM) may crash when processing fragmented packets. This vulnerability affects TMM through a virtual server configured with a FastL4 profile. Traffic processing is disrupted while TMM restarts. If the affected BIG-IP system is configured as part of a device group, it will trigger a failover to the peer device.
https://support.f5.com/csp/article/K65615624