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Actively exploited

CVE-2023-20867 VMware Tools Authentication Bypass Vulnerability

VMware Tools contains an authentication bypass vulnerability in the vgauth module. A fully compromised ESXi host can force VMware Tools to fail to authenticate host-to-guest operations, impacting the confidentiality and integrity of the guest virtual machine. An attacker must have root access over ESXi to exploit this vulnerability.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch urgentlyCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 23 Jun 2023.
  • Rated Low severity (CVSS 3.9, scored by Vendor).
  • It has been in the catalogue for 1,232 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

A fully compromised ESXi host can force VMware Tools to fail to authenticate host-to-guest operations, impacting the confidentiality and integrity of the guest virtual machine.

Affected Versions

ProductVersions
VMware VMware ToolsSee the vendor advisory

From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for VMware Tools. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply updates per vendor instructions.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsCyber Essentials requires high and critical updates (CVSS 7.0 or above) within 14 days of release. Treat any exploited flaw the same way.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 14 Jul 2023 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

More Exploited VMware Flaws

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CVE-2025-22226VMware ESXi, Workstation, and Fusion Information Disclosure VulnerabilityAdded 4 Mar 2025CVE-2025-22225 · RansomwareVMware ESXi Arbitrary Write VulnerabilityAdded 4 Mar 2025CVE-2025-22224VMware ESXi and Workstation TOCTOU Race Condition VulnerabilityAdded 4 Mar 2025CVE-2024-38813VMware vCenter Server Privilege Escalation VulnerabilityAdded 20 Nov 2024CVE-2024-38812VMware vCenter Server Heap-Based Buffer Overflow VulnerabilityAdded 20 Nov 2024CVE-2024-37085 · RansomwareVMware ESXi Authentication Bypass VulnerabilityAdded 30 Jul 2024

All 26 exploited VMware vulnerabilities

Not Sure If You Are Exposed?

Our attack surface and vulnerability teams can check your internet-facing estate for CVE-2023-20867 and every other exploited flaw on the list.

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2023-20867
  3. CVE record: CVE-2023-20867
  4. FIRST EPSS
  5. vmware.com/security/advisories/VMSA-2023-0013.html
  6. security.netapp.com/advisory/ntap-20230725-0001/
  7. lists.debian.org/debian-lts-announce/2023/08/msg00020.html
  8. debian.org/security/2023/dsa-5493
  9. lists.fedoraproject.org/archives/list/[email protected]/message/ZJM6HDRQYS74J
  10. lists.fedoraproject.org/archives/list/[email protected]/message/NVKQ6Y2JFJRWP
  11. lists.fedoraproject.org/archives/list/[email protected]/message/TJNJMD67QIT6L
  12. openwall.com/lists/oss-security/2023/10/16/2