The default configuration of the IPsec IKE peer listener in F5 BIG-IP LTM, Analytics, APM, ASM, and Link Controller 11.2.1 before HF16, 11.4.x, 11.5.x before 11.5.4 HF2, 11.6.x before 11.6.1, and 12.x before 12.0.0 HF2; BIG-IP AAM, AFM, and PEM 11.4.x, 11.5.x before 11.5.4 HF2, 11.6.x before 11.6.1, and 12.x before 12.0.0 HF2; BIG-IP DNS 12.x before 12.0.0 HF2; BIG-IP Edge Gateway, WebAccelerator, and WOM 11.2.1 before HF16; BIG-IP GTM 11.2.1 before HF16, 11.4.x, 11.5.x before 11.5.4 HF2, and 11.6.x before 11.6.1; and BIG-IP PSM 11.4.0 through 11.4.1 improperly enables the anonymous IPsec IKE peer configuration object, which allows remote attackers to establish an IKE Phase 1 negotiation and possibly conduct brute-force attacks against Phase 2 negotiations via unspecified vectors.
https://support.f5.com/kb/en-us/solutions/public/k/10/sol10133477.html