CVE-2020-5941

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: 2020-11-05 · updated 2026-06-17

Description

On BIG-IP versions 16.0.0-16.0.0.1 and 15.1.0-15.1.0.5, using the RESOLV::lookup command within an iRule may cause the Traffic Management Microkernel (TMM) to generate a core file and restart. This issue occurs when data exceeding the maximum limit of a hostname passes to the RESOLV::lookup command.

Affected products

F5 BIG-IP APM: from 15.1.0 before 15.1.1; from 16.0.0 before 16.0.1 — fixed in 15.1.1, 16.0.1
BIG-IP: from 15.1.0 before 15.1.1; from 16.0.0 before 16.0.1 — fixed in 15.1.1, 16.0.1
F5 Big-Ip Analytics: from 15.1.0 before 15.1.1; from 16.0.0 before 16.0.1 — fixed in 15.1.1, 16.0.1
F5 Networks, Inc. BIG-IP (AAM): from 15.1.0 before 15.1.1; from 16.0.0 before 16.0.1 — fixed in 15.1.1, 16.0.1
BIG-IP ASM: from 15.1.0 before 15.1.1; from 16.0.0 before 16.0.1 — fixed in 15.1.1, 16.0.1
F5 BIG-IP DNS: from 15.1.0 before 15.1.1; from 16.0.0 before 16.0.1 — fixed in 15.1.1, 16.0.1
F5 Big-Ip Fraud Protection Service: from 15.1.0 before 15.1.1; from 16.0.0 before 16.0.1 — fixed in 15.1.1, 16.0.1
F5 Big-Ip Global Traffic Manager: from 15.1.0 before 15.1.1; from 16.0.0 before 16.0.1 — fixed in 15.1.1, 16.0.1
F5 Big-Ip Link Controller: from 15.1.0 before 15.1.1; from 16.0.0 before 16.0.1 — fixed in 15.1.1, 16.0.1
F5 BIG-IP (LTM): from 15.1.0 before 15.1.1; from 16.0.0 before 16.0.1 — fixed in 15.1.1, 16.0.1
F5 Networks, Inc. BIG-IP (PEM): from 15.1.0 before 15.1.1; from 16.0.0 before 16.0.1 — fixed in 15.1.1, 16.0.1

How to fix

Upgrade to a fixed version: F5 BIG-IP APM 15.1.1, 16.0.1; BIG-IP 15.1.1, 16.0.1; F5 Big-Ip Analytics 15.1.1, 16.0.1; F5 Networks, Inc. BIG-IP (AAM) 15.1.1, 16.0.1; BIG-IP ASM 15.1.1, 16.0.1; F5 BIG-IP DNS 15.1.1, 16.0.1; F5 Big-Ip Fraud Protection Service 15.1.1, 16.0.1; F5 Big-Ip Global Traffic Manager 15.1.1, 16.0.1; F5 Big-Ip Link Controller 15.1.1, 16.0.1; F5 BIG-IP (LTM) 15.1.1, 16.0.1; F5 Networks, Inc. BIG-IP (PEM) 15.1.1, 16.0.1. Check the vendor advisory for mitigations.

References

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