What is CVE-2026-42920?

CVE-2026-42920 is a high-severity vulnerability in F5 Big-ip, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 7.5/10. Published 2026-05-13.

How severe is CVE-2026-42920?

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

Vulnerability in F5 Big-ip

CVE-2026-42920

When a Client SSL profile is configured with Allow Dynamic Record Sizing on a UDP virtual server, undisclosed traffic can cause the Traffic Management Microkernel (TMM) to terminate. Note: Software versions which have reached End of Techn…

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-835 — Loop with Unreachable Exit Condition (Infinite Loop)

References

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

Frequently asked questions

What is CVE-2026-42920?: CVE-2026-42920 is a high-severity vulnerability in F5 Big-ip, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 7.5/10. Published 2026-05-13.
How severe is CVE-2026-42920?: High severity. CVSS v3 base score is 7.5 out of 10.