CVE-2020-27721: F5 BIG-IP Domain Name System

High severity, CVSS 7.5. EPSS: 1% chance of exploitation in the next 30 days.

In versions 16.0.0-16.0.0.1, 15.1.0-15.1.1, 14.1.0-14.1.3, 13.1.0-13.1.3.5, 12.1.0-12.1.5.2, and 11.6.1-11.6.5.2, in a BIG-IP DNS / BIG-IP LTM GSLB deployment, under certain circumstances, the BIG-IP DNS system may stop using a BIG-IP LTM virtual server for DNS response.

Affected products

• F5 BIG-IP Domain Name System: from 11.6.1, up to and including 11.6.5; from 12.1.0, up to and including 12.1.5; 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 15.0.0, before 15.1.2 (fixed in 15.1.2); from 16.0.0, before 16.0.1 (fixed in 16.0.1)
• F5 BIG-IP Global Traffic Manager: from 11.6.1, up to and including 11.6.5; from 12.1.0, up to and including 12.1.5; 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 15.0.0, before 15.1.2 (fixed in 15.1.2); from 16.0.0, before 16.0.1 (fixed in 16.0.1)

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