DoS via HTTP::redirect/HTTP::respond iRule on F5 BIG-IP TMM
CVE-2026-42409 Published on May 13, 2026
BIG-IP HTTP/2 vulnerability
When an HTTP/2 profile and an iRule containing the HTTP::redirect or HTTP::respond command are configured on a virtual server, undisclosed requests can cause the Traffic Management Microkernel (TMM) process to terminate. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Vulnerability Analysis
CVE-2026-42409 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Type
NULL Pointer Dereference
A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions.
Products Associated with CVE-2026-42409
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Affected Versions
F5 BIG-IP:- Version 21.1.0 and below * is unaffected.
- Version 21.0.0 and below 21.0.0.1 is affected.
- Version 17.5.0 and below 17.5.1.4 is affected.
- Version 17.1.0 and below 17.1.3.1 is affected.
- Version 16.1.0 and below * is affected.
- Version 2.0.0 and below 2.0.3 is affected.
- Version 1.7.0 and below 1.7.17 is affected.
- Version 2.0.0 and below 2.0.3 is affected.
- Version 1.4.0 and below 1.4.1 is affected.
- Version 2.0.0 and below 2.1.1 is affected.