Is CVE-2026-39458 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-39458 being exploited in the wild.

How severe is CVE-2026-39458?

High severity, with a CVSS score of 7.5, published 13 May 2026.

Which products and versions are affected?

F5 BIG-IP DNS 16.1.0 - 16.1.6, 17.5.0 - 17.5.1, 21.0.0, Undisclosed (EoTS versions excluded); F5 Big-Ip Access Policy Manager 16.1.0 - 16.1.6, 17.5.0 - 17.5.1, 21.0.0; F5 Big-Ip Advanced Firewall Manager 16.1.0 - 16.1.6, 17.5.0 - 17.5.1, 21.0.0; F5 Big-Ip Local Traffic Manager 16.1.0 - 16.1.6, 17.5.0 - 17.5.1, 21.0.0.

Is there a fix for CVE-2026-39458?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-39458 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2026-39458?

Check whether you run F5 BIG-IP DNS, F5 Big-Ip Access Policy Manager, F5 Big-Ip Advanced Firewall Manager or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-39458: F5 BIG-IP TMM denial of service in DNS cache profile

CVE-2026-39458 · Severity: high · CVSS 7.5 · Published 2026-05-13

F5 BIG-IP is a suite of networking devices used to manage and secure enterprise web traffic. A vulnerability in the DNS caching feature allows a remote attacker to send specific network traffic that crashes the system's core processing engine. This results in a complete service outage, preventing legitimate users from accessing applications protected or managed by the affected BIG-IP device.

Technologies: F5 BIG-IP DNS, F5 Big-Ip Access Policy Manager, F5 Big-Ip Advanced Firewall Manager, F5 Big-Ip Local Traffic Manager. Vendors: F5.

Quick answers

Is CVE-2026-39458 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-39458 being exploited in the wild.
How severe is CVE-2026-39458?: High severity, with a CVSS score of 7.5, published 13 May 2026.
Which products and versions are affected?: F5 BIG-IP DNS 16.1.0 - 16.1.6, 17.5.0 - 17.5.1, 21.0.0, Undisclosed (EoTS versions excluded); F5 Big-Ip Access Policy Manager 16.1.0 - 16.1.6, 17.5.0 - 17.5.1, 21.0.0; F5 Big-Ip Advanced Firewall Manager 16.1.0 - 16.1.6, 17.5.0 - 17.5.1, 21.0.0; F5 Big-Ip Local Traffic Manager 16.1.0 - 16.1.6, 17.5.0 - 17.5.1, 21.0.0.
Is there a fix for CVE-2026-39458?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-39458 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-39458?: Check whether you run F5 BIG-IP DNS, F5 Big-Ip Access Policy Manager, F5 Big-Ip Advanced Firewall Manager or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A denial-of-service vulnerability exists in F5 BIG-IP when a DNS profile with DNS cache is enabled on a virtual server. The issue is rooted in an 'Access of Uninitialized Pointer' (CWE-824) within the Traffic Management Microkernel (TMM). A remote, unauthenticated attacker can send undisclosed network traffic to the virtual server, triggering a TMM crash and subsequent system restart. This affects multiple BIG-IP modules including DNS, LTM, AFM, and APM across versions 16.1.x, 17.5.x, and 21.0.0. F5 has released advisory K000160945 to address the issue.

Affected products

F5 BIG-IP DNS 16.1.0 - 16.1.6, 17.5.0 - 17.5.1, 21.0.0
F5 BIG-IP Access Policy Manager 16.1.0 - 16.1.6, 17.5.0 - 17.5.1, 21.0.0
F5 BIG-IP Advanced Firewall Manager 16.1.0 - 16.1.6, 17.5.0 - 17.5.1, 21.0.0
F5 BIG-IP Local Traffic Manager 16.1.0 - 16.1.6, 17.5.0 - 17.5.1, 21.0.0

Timeline

2026-05-13: advisory: Initial publication of the vulnerability advisory

References

https://my.f5.com/manage/s/article/K000160945

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