CVE-2026-42920: BIG-IP DTLS Vulnerability

Published May 13, 2026
·
Updated

When a Client SSL profile is configured with Allow Dynamic Record Sizing on a UDP virtual server, undisclosed traffic can cause the Traffic Management Microkernel (TMM) to terminate.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Affected Software

85 affected components
F5 Networks BIG-IP
F5 BIG-IP Access Policy Manager=21.0.0
F5 BIG-IP Advanced Firewall Manager=21.0.0
F5 Big-ip Advanced Web Application Firewall=21.0.0
F5 BIG-IP Analytics=21.0.0
F5 Big-ip Application Acceleration Manager=21.0.0
F5 BIG-IP Application Security Manager=21.0.0
F5 Big-ip Application Visibility And Reporting=21.0.0
F5 Big-ip Automation Toolchain=21.0.0
F5 Big-ip Carrier-grade Nat=21.0.0
F5 BIG-IP Container Ingress Services=21.0.0
F5 Big-ip Ddos Hybrid Defender=21.0.0
F5 Big-ip Domain Name System=21.0.0
F5 BIG-IP Edge Gateway=21.0.0
F5 Big-ip Fraud Protection Service=21.0.0
F5 Big-ip Global Traffic Manager=21.0.0
F5 Big-ip Link Controller=21.0.0
F5 Big-ip Local Traffic Manager=21.0.0
F5 Big-ip Policy Enforcement Manager=21.0.0
F5 BIG-IP SSL Orchestrator=21.0.0
F5 Big-ip Webaccelerator=21.0.0
F5 Big-ip Websafe=21.0.0
F5 BIG-IP Access Policy Manager>=17.1.0<=17.1.3
F5 BIG-IP Access Policy Manager>=17.5.0<=17.5.1
F5 BIG-IP Advanced Firewall Manager>=17.1.0<=17.1.3
F5 BIG-IP Advanced Firewall Manager>=17.5.0<=17.5.1
F5 Big-ip Advanced Web Application Firewall>=17.1.0<=17.1.3
F5 Big-ip Advanced Web Application Firewall>=17.5.0<=17.5.1
F5 BIG-IP Analytics>=17.1.0<=17.1.3
F5 BIG-IP Analytics>=17.5.0<=17.5.1
F5 Big-ip Application Acceleration Manager>=17.1.0<=17.1.3
F5 Big-ip Application Acceleration Manager>=17.5.0<=17.5.1
F5 BIG-IP Application Security Manager>=17.1.0<=17.1.3
F5 BIG-IP Application Security Manager>=17.5.0<=17.5.1
F5 Big-ip Application Visibility And Reporting>=17.1.0<=17.1.3
F5 Big-ip Application Visibility And Reporting>=17.5.0<=17.5.1
F5 Big-ip Automation Toolchain>=17.1.0<=17.1.3
F5 Big-ip Automation Toolchain>=17.5.0<=17.5.1
F5 Big-ip Carrier-grade Nat>=17.1.0<=17.1.3
F5 Big-ip Carrier-grade Nat>=17.5.0<=17.5.1
F5 BIG-IP Container Ingress Services>=17.1.0<=17.1.3
F5 BIG-IP Container Ingress Services>=17.5.0<=17.5.1
F5 Big-ip Ddos Hybrid Defender>=17.1.0<=17.1.3
F5 Big-ip Ddos Hybrid Defender>=17.5.0<=17.5.1
F5 Big-ip Domain Name System>=17.1.0<=17.1.3
F5 Big-ip Domain Name System>=17.5.0<=17.5.1
F5 BIG-IP Edge Gateway>=17.1.0<=17.1.3
F5 BIG-IP Edge Gateway>=17.5.0<=17.5.1
F5 Big-ip Fraud Protection Service>=17.1.0<=17.1.3
F5 Big-ip Fraud Protection Service>=17.5.0<=17.5.1
F5 Big-ip Global Traffic Manager>=17.1.0<=17.1.3
F5 Big-ip Global Traffic Manager>=17.5.0<=17.5.1
F5 Big-ip Link Controller>=17.1.0<=17.1.3
F5 Big-ip Link Controller>=17.5.0<=17.5.1
F5 Big-ip Local Traffic Manager>=17.1.0<=17.1.3
F5 Big-ip Local Traffic Manager>=17.5.0<=17.5.1
F5 Big-ip Policy Enforcement Manager>=17.1.0<=17.1.3
F5 Big-ip Policy Enforcement Manager>=17.5.0<=17.5.1
F5 BIG-IP SSL Orchestrator>=17.1.0<=17.1.3
F5 BIG-IP SSL Orchestrator>=17.5.0<=17.5.1
F5 Big-ip Webaccelerator>=17.1.0<=17.1.3
F5 Big-ip Webaccelerator>=17.5.0<=17.5.1
F5 Big-ip Websafe>=17.1.0<=17.1.3
F5 Big-ip Websafe>=17.5.0<=17.5.1
F5 BIG-IP Access Policy Manager>=16.1.0<=16.1.6
F5 BIG-IP Advanced Firewall Manager>=16.1.0<=16.1.6
F5 Big-ip Advanced Web Application Firewall>=16.1.0<=16.1.6
F5 BIG-IP Analytics>=16.1.0<=16.1.6
F5 Big-ip Application Acceleration Manager>=16.1.0<=16.1.6
F5 BIG-IP Application Security Manager>=16.1.0<=16.1.6
F5 Big-ip Application Visibility And Reporting>=16.1.0<=16.1.6
F5 Big-ip Automation Toolchain>=16.1.0<=16.1.6
F5 Big-ip Carrier-grade Nat>=16.1.0<=16.1.6
F5 BIG-IP Container Ingress Services>=16.1.0<=16.1.6
F5 Big-ip Ddos Hybrid Defender>=16.1.0<=16.1.6
F5 Big-ip Domain Name System>=16.1.0<=16.1.6
F5 BIG-IP Edge Gateway>=16.1.0<=16.1.6
F5 Big-ip Fraud Protection Service>=16.1.0<=16.1.6
F5 Big-ip Global Traffic Manager>=16.1.0<=16.1.6
F5 Big-ip Link Controller>=16.1.0<=16.1.6
F5 Big-ip Local Traffic Manager>=16.1.0<=16.1.6
F5 Big-ip Policy Enforcement Manager>=16.1.0<=16.1.6
F5 BIG-IP SSL Orchestrator>=16.1.0<=16.1.6
F5 Big-ip Webaccelerator>=16.1.0<=16.1.6
F5 Big-ip Websafe>=16.1.0<=16.1.6

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Configuration

    Disable the 'Allow Dynamic Record Sizing' option in the Client SSL profile for any UDP virtual server to prevent undisclosed traffic from causing the Traffic Management Microkernel (TMM) to terminate.

    BIG-IP Client SSL profile (used on UDP virtual servers) Allow Dynamic Record Sizing = disabled

Event History

May 13, 2026
CVE Published
via MITRE·02:12 PM
Data Sourced
via MITRE·02:12 PM
DescriptionSeverityWeakness
Data Sourced
via NVD·04:16 PM
DescriptionSeverityWeaknessAffected Software
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Frequently Asked Questions

1

What is the severity of CVE-2026-42920?

The severity of CVE-2026-42920 is rated high with a score of 8.7.

2

How do I fix CVE-2026-42920?

To fix CVE-2026-42920, ensure that the Client SSL profile does not have Allow Dynamic Record Sizing enabled on UDP virtual servers.

3

What software is affected by CVE-2026-42920?

CVE-2026-42920 affects multiple F5 BIG-IP software products, including Access Policy Manager and Advanced Firewall Manager.

4

What is the impact of CVE-2026-42920?

CVE-2026-42920 can lead to the termination of the Traffic Management Microkernel, affecting service availability.

5

Is there any workaround for CVE-2026-42920?

Currently, the best workaround for CVE-2026-42920 is to disable the Allow Dynamic Record Sizing feature on vulnerable UDP virtual servers.

Company

Resources

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