CVE-2021-23000

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: 2021-03-31 · updated 2026-06-17

Description

On BIG-IP versions 13.1.3.4-13.1.3.6 and 12.1.5.2, if the tmm.http.rfc.enforcement BigDB key is enabled in a BIG-IP system, or the Bad host header value is checked in the AFM HTTP security profile associated with a virtual server, in rare instances, a specific sequence of malicious requests may cause TMM to restart. Note: Software versions which have reached End of Software Development (EoSD) are not evaluated.

Affected products

F5 BIG-IP APM: from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6
BIG-IP: from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6
F5 Big-Ip Advanced Web Application Firewall: from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6
F5 Big-Ip Analytics: from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6
F5 Networks, Inc. BIG-IP (AAM): from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6
BIG-IP ASM: from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6
F5 Big-Ip Ddos Hybrid Defender: from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6
F5 BIG-IP DNS: from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6
F5 Big-Ip Fraud Protection Service: from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6
F5 Big-Ip Global Traffic Manager: from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6
F5 Big-Ip Link Controller: from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6
F5 BIG-IP (LTM): from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6
F5 Networks, Inc. BIG-IP (PEM): from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6
F5 SSL Orchestrator: from 13.1.3.4 before 13.1.3.6; 12.1.5.2 — fixed in 13.1.3.6

How to fix

Upgrade to a fixed version: F5 BIG-IP APM 13.1.3.6; BIG-IP 13.1.3.6; F5 Big-Ip Advanced Web Application Firewall 13.1.3.6; F5 Big-Ip Analytics 13.1.3.6; F5 Networks, Inc. BIG-IP (AAM) 13.1.3.6; BIG-IP ASM 13.1.3.6; F5 Big-Ip Ddos Hybrid Defender 13.1.3.6; F5 BIG-IP DNS 13.1.3.6; F5 Big-Ip Fraud Protection Service 13.1.3.6; F5 Big-Ip Global Traffic Manager 13.1.3.6; F5 Big-Ip Link Controller 13.1.3.6; F5 BIG-IP (LTM) 13.1.3.6. Check the vendor advisory for mitigations.

References

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