When F5 BIG-IP 13.0.0-13.1.0.5, 12.1.0-12.1.3.5, 11.6.0-11.6.3.2, or 11.5.1-11.5.6 is processing specially crafted TCP traffic with the Large Receive Offload (LRO) feature enabled, TMM may crash, leading to a failover event. This vulnerability is not exposed unless LRO is enabled, so most affected customers will be on 13.1.x. LRO has been available since 11.4.0 but is not enabled by default until 13.1.0.
The Linux kernel, versions 3.9+, is vulnerable to a denial of service attack with low rates of specially modified packets targeting IP fragment re-assembly. An attacker may cause a denial of service condition by sending specially crafted IP fragments. Various vulnerabilities in IP fragmentation have been discovered and fixed over the years. The current vulnerability (CVE-2018-5391) became exploitable in the Linux kernel with the increase of the IP fragment reassembly queue size.
Through undisclosed methods, on F5 BIG-IP 13.0.0-13.1.0.7, 12.1.0-12.1.3.5, 11.6.0-11.6.3.1, or 11.2.1-11.5.6, adjacent network attackers can cause a denial of service for VCMP guest and host systems. Attack must be sourced from adjacent network (layer 2).
A remote attacker may be able to disrupt services on F5 BIG-IP 13.0.0-13.1.0.5, 12.1.0-12.1.3.5, 11.6.0-11.6.3.1, or 11.2.1-11.5.6 if the TMM virtual server is configured with a HTML or a Rewrite profile. TMM may restart while processing some specially prepared HTML content from the back end.