BIG-IP
CVE-2026-41218: BIG-IP PEM iRules vulnerability
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.
Published
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| BIG-IP 21.1 | Not affected |
| BIG-IP 21.0 | 21.0.0.1 or later |
| BIG-IP 17.5 | 17.5.1.4 or later |
| BIG-IP 17.1 | 17.1.3.1 or later |
| BIG-IP 16.1 | * or later |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
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.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 12 Oct 2026.