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K75111593: BIG-IP VE network interface vulnerability CVE-2020-5939

Original Publication Date: Nov 03, 2020

Security Advisory Description

BIG-IP Virtual Edition (VE) systems on VMware, with an Intel-based 85299 Network Interface Controller (NIC) card and Single Root I/O Virtualization (SR-IOV) enabled on vSphere, may fail and leave the Traffic Management Microkernel (TMM) in a state where it cannot transmit traffic. (CVE-2020-5939)

Impact

TMM fails to process traffic, resulting in service disruption. If the affected BIG-IP system is configured as part of a device group, the system triggers a failover to the peer device.

Security Advisory Status

F5 Product Development has assigned ID 891457 (BIG-IP) to this vulnerability.

To determine if your product and version have been evaluated for this vulnerability, refer to the Applies to (see versions) box. To determine if your release is known to be vulnerable, the components or features that are affected by the vulnerability, and for information about releases, point releases, or hotfixes that address the vulnerability, refer to the following table. For more information about security advisory versioning, refer to K51812227: Understanding security advisory versioning.

Product Branch Versions known to be vulnerable Fixes introduced in Severity CVSSv3 score1 Vulnerable component or feature
BIG-IP (LTM, AAM, Advanced WAF, AFM, Analytics, APM, ASM, DDHD, DNS, FPS, GTM, Link Controller, PEM, SSLO)
16.x 16.0.0 16.0.1 High 7.5 TMM
15.x 15.1.0 15.1.0.4
14.x 14.1.0 – 14.1.2 14.1.2.7
13.x 13.1.0 – 13.1.3 None
12.x None Not applicable
11.x None Not applicable
BIG-IQ Centralized Management
7.x None Not applicable Not vulnerable None None
6.x None Not applicable
5.x None Not applicable Not vulnerable None None
Traffix SDC
5.x

1The CVSSv3 score link takes you to a resource outside of AskF5, and it is possible that the document may be removed without our knowledge.

Security Advisory Recommended Actions

If you are running a version listed in the Versions known to be vulnerable column, you can eliminate this vulnerability by upgrading to a version listed in the Fixes introduced in column. If the table lists only an older version than what you are currently running, or does not list a non-vulnerable version, then no upgrade candidate currently exists.

Mitigation

To mitigate this vulnerability, you can disable TCP Segmentation Offload (TSO). You can do so by setting the value of the tm.tcpsegmentationoffload BigDB key to disable and restarting TMM. To do so, perform the following procedure:

Note: For more information about TSO, refer to K15609: Overview of TCP Segmentation Offload and Large Receive Offload.

Impact of action: The impact of the suggested mitigation depends on the specific environment. F5 recommends testing any such changes during a maintenance window with consideration to the possible impact on your specific environment. Additionally, restarting TMM temporarily interrupts traffic processing.

  1. Log in to the tmsh utility by typing the following command:
    tmsh
  2. Disable TSO by entering the following command:
    modify sys db tm.tcpsegmentationoffload value disable
  3. Restart TMM by entering the following command:
    restart /sys service tmm

Supplemental Information