---
id: CVE-2026-41218
title: >-
  When BIG-IP PEM iRules are configured on a virtual server (iRules using
  commands starting with CLASSIFICATION::, CLASSIFY::, PEM::, PSC::, and the
  urlcatquery command), undisclosed traffic can cause the Traffic Management
  Microkernel (TM…
summary: >-
  When BIG-IP PEM iRules are configured on a virtual server (iRules using
  commands starting with CLASSIFICATION::, CLASSIFY::, PEM::, PSC::, and the
  urlcatquery command), undisclosed traffic can cause the Traffic Management
  Microkernel (TM…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-416
published: '2026-05-13'
updated: '2026-06-24'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-41218'
references:
  - url: 'https://my.f5.com/manage/s/article/K000160875'
    label: f5sirt@f5.com
tags:
  - nvd
epss: 0.00263
epssPercentile: 0.18448
ingestedAt: '2026-06-29T13:24:35.015Z'
---

## Overview

When BIG-IP PEM iRules are configured on a virtual server (iRules using commands starting with CLASSIFICATION::, CLASSIFY::, PEM::, PSC::, and the urlcatquery command), 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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.