CVE-2021-23042

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-09-14 · updated 2026-06-17
Weakness: CWE-400

Description

On BIG-IP version 16.0.x before 16.0.1.2, 15.1.x before 15.1.3, 14.1.x before 14.1.4, 13.1.x before 13.1.4, and 12.1.x before 12.1.6, when an HTTP profile is configured on a virtual server, undisclosed requests can cause a significant increase in system resource utilization. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Affected products

F5 BIG-IP APM: from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2
BIG-IP: from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2
F5 Big-Ip Advanced Web Application Firewall: from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2
F5 Big-Ip Analytics: from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2
F5 Networks, Inc. BIG-IP (AAM): from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2
BIG-IP ASM: from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2
F5 Big-Ip Ddos Hybrid Defender: from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2
F5 BIG-IP DNS: from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2
F5 Big-Ip Fraud Protection Service: from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2
F5 Big-Ip Global Traffic Manager: from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2
F5 Big-Ip Link Controller: from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2
F5 BIG-IP (LTM): from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2
F5 Networks, Inc. BIG-IP (PEM): from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2
F5 Big-Ip Ssl Orchestrator: from 12.1.0 before 12.1.6; from 13.1.0 before 13.1.4; from 14.1.0 before 14.1.4; from 15.1.0 before 15.1.3; from 16.0.0 before 16.0.1.2 — fixed in 12.1.6, 13.1.4, 14.1.4, 15.1.3, 16.0.1.2

How to fix

Upgrade to a fixed version: F5 BIG-IP APM 12.1.6, 13.1.4, 14.1.4, 15.1.3; BIG-IP 12.1.6, 13.1.4, 14.1.4, 15.1.3; F5 Big-Ip Advanced Web Application Firewall 12.1.6, 13.1.4, 14.1.4, 15.1.3; F5 Big-Ip Analytics 12.1.6, 13.1.4, 14.1.4, 15.1.3; F5 Networks, Inc. BIG-IP (AAM) 12.1.6, 13.1.4, 14.1.4, 15.1.3; BIG-IP ASM 12.1.6, 13.1.4, 14.1.4, 15.1.3; F5 Big-Ip Ddos Hybrid Defender 12.1.6, 13.1.4, 14.1.4, 15.1.3; F5 BIG-IP DNS 12.1.6, 13.1.4, 14.1.4, 15.1.3; F5 Big-Ip Fraud Protection Service 12.1.6, 13.1.4, 14.1.4, 15.1.3; F5 Big-Ip Global Traffic Manager 12.1.6, 13.1.4, 14.1.4, 15.1.3; F5 Big-Ip Link Controller 12.1.6, 13.1.4, 14.1.4, 15.1.3; F5 BIG-IP (LTM) 12.1.6, 13.1.4, 14.1.4, 15.1.3. Check the vendor advisory for mitigations.

References

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