CVE-2020-27721

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-12-24 · updated 2026-06-17

Description

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 DNS: from 11.6.1 through 11.6.5; from 12.1.0 through 12.1.5; from 13.1.0 through 13.1.3; from 14.1.0 before 14.1.3.1; from 15.0.0 before 15.1.2; from 16.0.0 before 16.0.1 — fixed in 14.1.3.1, 15.1.2, 16.0.1
F5 Big-Ip Global Traffic Manager: from 11.6.1 through 11.6.5; from 12.1.0 through 12.1.5; from 13.1.0 through 13.1.3; from 14.1.0 before 14.1.3.1; from 15.0.0 before 15.1.2; from 16.0.0 before 16.0.1 — fixed in 14.1.3.1, 15.1.2, 16.0.1

How to fix

Upgrade to a fixed version: F5 BIG-IP DNS 14.1.3.1, 15.1.2, 16.0.1; F5 Big-Ip Global Traffic Manager 14.1.3.1, 15.1.2, 16.0.1. Check the vendor advisory for mitigations.

References

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