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Spectre Vulnerability – How to Patch VMware ESXi

Yesterday, news broke about vulnerabilities affecting AMD, Intel, and ARM CPU’s. These vulnerabilities, termed Meltdown and Spectre, have the potential to expose information that the machine(s) process. Check out this post for an in-depth look. At this point, it appears that VMware is not vulnerable to Meltdown; however, they have released patches for Spectre. It has been speculated that patching the flaws will cause performance hits. To what degree varies by reporting source. As always, test patches before deployment and contact support if you have any questions.

As per the initial VMware Security Advisory, the specified patches should be applied for remediation. Remember, these patches remediate known issues. Definitely, watch for additional patches as exploits may continue to surface. If you are needing to patch your ESXi host per the advisory, you can do so through VMware Update Manager (VUM).

Update – VMware has removed patches to address Hypervisor-Assisted Guest Mitigation (VMSA-2018-04).

As a recap, patches have been released to address Hypervisor-Specific Remediation (VMSA-2018-02) and Hypervisor-Assisted Guest Remediation (VMSA-2018-04). For more detail, check out this VMware KB detailing these responses.

VMware Patch Numbers for ESXi Versions (VMSA-2018-02):

  • ESXi 6.5 – ESXi650-201712101-SG
  • ESXi 6.0 – ESXi600-201711101-SG
  • ESXi 5.5 – ESXi550-201709101-SG
    • This 5.5 patch only addresses CVE-2017-5715, not CVE-2017-5753

VMware Patch Numbers for ESXi Versions (VMSA-2018-04)

  • ESXi 6.5 – ESXi650-201801401-BG, ESXi650-201801402-BG
  • ESXi 6.0 – ESXi600-201801401-BG, ESXi600-201801402-BG
  • ESXi 5.5 – ESXi550-201801401-BG

For this example, we will be patching VMware ESXi 6.5 with patch ESXi650-201712101-SG. Additional patches can be applied in the same manner. Read the release notes or security advisories before patching as other components may need to be patched first.

Remediate ESXi

Let’s begin! Log in to the vSphere web client and select the host or cluster for remediation. Locate the Update Manager tab and select Attach Baseline.

Attach Baseline

From the Patch Baselines, select Non-Critical and Critical Host Patches. Press OK.

Attach Baseline

Click Scan for Updates, to verify compliance.

Scan Compliance

If patching is needed, the compliance status will come back as Non-Compliant.


In the non-compliant list, we can see our host is missing the ESXi650-201712101-SG patch.

ESXi Spectre Patch

Next, we will set the remediation options. Click Remediate to begin the process.

Remediate Patches

Select the patch baselines to remediate.

Select Baseline

Select the host(s) for remediation.

Remediate HP Target

Select the specific patch to apply.

Select Patch

In the Advanced Options section, we can schedule a specific remediation time and/or choose to ignore unsupported items.

Remediate HP Advanced Options

Next, specify Host Remediation Options. Set power state options, disable removable media, and designate maintenance mode retries here.

Remediate Options

Lastly, specify the Cluster Remediation Options.  For hosts in a cluster, the remediation process runs in a sequential manner. If you prefer to run the remediation in parallel, indicate that here.

Remediate HP Cluster

Review selections and click Finish to begin the remediation process.

Remediate HP Review

Progress can be monitored in the Recent Tasks pane. Update Manager performs the following remediation items:

  • Enters host in maintenance mode. Migrating virtual machines to other hosts if applicable.
  • Applies specified patch.
  • Restarts host.
  • Re-connects host to vCenter.
  • Exits host from maintenance mode.
  • Remediates additional host(s) if appropriate.

Recent Tasks

Once the remediation is complete, the baseline shows compliant.

From early reports, admins will want to patch Guest Operating Systems as well.

VMware Security and Compliance Blog Post – VMSA-2018-0002

VMware Security and Compliance Blog Post – VMSA-2018-0004

VMware – Intel Sightings in ESXi Bundled Microcode Patches for VMSA-2018-0004

Intel News Release

Related Posts


  1. Is it needed to patch the OS in all the virtual machines which are running on the patched VM host ?

  2. Awesome guide. Does this patch require a restart?

  3. Thank you for the step by step instructions. Do you know whether we need to patch vCenter appliance as well?

  4. the release date of the patch( for esxi 5.5 ) is Release date: September 14, 2017
    vmware kown this bug before ?

  5. Hi
    I have created a baseline that include all critical patches for 6.0.

    ESXi600-201711401-BG is getting installed but ESXi600-201711101-SG is showing as as obsolete by host.

    Does this means that i am still vulnerable?

  6. This is a great guide. Love the site!

  7. Have read the hosts need to be patched BEFORE guest updates.

    Has anyone done the above and seen any performance hit to ESX or longer CPU scheduling times in their environments?


  8. What about ESXi 5.1 ? I have a old HP GEN 6 server who is running this version

    • HP is in the process of rolling new Firmware updates for the various blades. Older, potentially unsupported, equipment may be an issue.

      They are indicating February for most of there blades, but i have seen anything other than info about G9/8/7…

  9. VMware still hasn’t released all of the patches yet, so it’s hard to say the true performance impact.

    • VMware has indicate an “insignificant” change in perform at the hypervisor level.

      However, you absolutely need hardware version 9 or higher to help mitigate guest patch performance issues. 11 is prefered…

      At least its nit Azure… I understand Microsoft is having a much more difficult time of it.

  10. When I scan I see a patch ESXi650-201712401BG. Could that be it? I do not se the 12101 patch.

  11. Funny… how to get a Vsphere client with ESXi 6.5?
    Noway to get that…. have to install the patch manually too bad it is still not in the web client version.
    Or am i missing something?

  12. Question about ESXi600-201711101-SG, my update manager says its Obsoleted by the Host What does this mean? Is it installed? I am now to believe my host is not patched.

    Thanks for any advice!

    • it means system already installed newer update that contains one you are trying to install and as result installing ESXi600-201711101-SG is no longer required (has been installed as part of generic update).

  13. What is the difference between the Hypervisor-Assisted Guest Mitigation patch and the one installed here which only patches the host?

    I am having a hard time sorting that out. DO you install both…or one or the other?

  14. Folks,

    There are three things you need to do, and in a specific order:

    – Update you vCenters to the current version
    – Update your hosts with the most recent patches (201801401)
    – Ensure you’ve applied either OEM firmware updates to your hosts OR apply the VMware microcode Patch (201801402)

    Its my understanding that ESXi will update the CPU microcode for processors that are relatively current.

    Complete info is here:


  15. Folks,

    VMware has pulled the patches; only the original patches are now available.

    They are recommending that you get firmware updates from your hardware manufacturer, and apply those.

    Of course, not all manufacturers are upating all of their platforms.

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