PT-2026-40675 · F5 · Big-Ip

Published 2026-05-13 · Updated 2026-05-17 · CVE-2026-42920

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions F5 BIG-IP versions prior to 17.1.3.1 F5 BIG-IP versions prior to 17.5.1.4 F5 BIG-IP versions prior to 21.0.0.1

Description 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. This issue can lead to an infinite loop within the TMM.

Recommendations Update to version 17.1.3.1 or later. Update to version 17.5.1.4 or later. Update to version 21.0.0.1 or later.

Fix

Infinite Loop

Weakness Enumeration

CWE-835

Related Identifiers

CVE-2026-42920

Affected Products

Big-Ip

References · 3

• https://nvd.nist.gov/vuln/detail/CVE-2026-42920 · Security Note
• https://my.f5.com/manage/s/article/K000160901 · Patch, Vendor Advisory
• https://twitter.com/f1tym1/status/2056025519464820946 · Twitter Post