CVE-2020-27720: F5 BIG-IP Carrier-Grade Nat

High severity, CVSS 7.5. EPSS: 1.4% chance of exploitation in the next 30 days.

On BIG-IP LTM/CGNAT version 16.0.0-16.0.0.1, 15.1.0-15.1.0.5, 14.1.0-14.1.3, and 13.1.0-13.1.3.5, when processing NAT66 traffic with Port Block Allocation (PBA) mode and SP-DAG enabled, and dag-ipv6-prefix-len configured with a value less than the default of 128, an undisclosed traffic pattern may cause the Traffic Management Microkernel (TMM) to restart.

Affected products

• F5 BIG-IP Carrier-Grade Nat: from 13.1.0, up to and including 13.1.3; from 14.1.0, before 14.1.3.1 (fixed in 14.1.3.1); from 15.1.0, before 15.1.1 (fixed in 15.1.1); from 16.0.0, before 16.0.1 (fixed in 16.0.1)
• F5 BIG-IP Local Traffic Manager: from 13.1.0, up to and including 13.1.3; from 14.1.0, before 14.1.3.1 (fixed in 14.1.3.1); from 15.1.0, before 15.1.1 (fixed in 15.1.1); from 16.0.0, before 16.0.1 (fixed in 16.0.1)

Published 2020-12-24. Last modified 2026-06-17.