What is CVE-2026-41218?

CVE-2026-41218 is a high-severity vulnerability in F5 Big-ip, classified under Use After Free. CVSS score: 7.5/10. Published 2026-05-13.

How severe is CVE-2026-41218?

High severity. CVSS v3 base score is 7.5 out of 10.

Use After Free in F5 Big-ip

CVE-2026-41218

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)…

Vulnerability class: Use-After-Free

EPSS: 0.001 (27.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

F5 Big-ip — versions 21.1.0, 21.0.0, 17.5.0

Weakness classification (CWE)

CWE-416 — Use After Free

References

f5sirt@f5.com (vendor-advisory, patch)

Frequently asked questions

What is CVE-2026-41218?: CVE-2026-41218 is a high-severity vulnerability in F5 Big-ip, classified under Use After Free. CVSS score: 7.5/10. Published 2026-05-13.
How severe is CVE-2026-41218?: High severity. CVSS v3 base score is 7.5 out of 10.