# CVE-2026-83839: Windows Hyper-V privilege escalation via race condition

Source: https://junglewise.ai/threats/cve-2026-83839-time-of-check-time-of-use-toctou-race-condition-in-windows-hyper  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-83839 · Severity: high · CVSS 7 · Published 2026-10-13

Windows Hyper-V, Microsoft's virtualization platform used to run virtual machines on Windows servers and desktops, contains a race condition that allows an authorized attacker to escalate privileges on the host system. An attacker with local access to the system could exploit this vulnerability to gain elevated privileges and take full control of the affected machine.

Technologies: [Microsoft Windows Hyper-V](https://junglewise.ai/threats/technologies/windows-hyper-v). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-83839 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-83839 being exploited in the wild.

**How severe is CVE-2026-83839?** High severity, with a CVSS score of 7, published 13 October 2026.

**Which products and versions are affected?** Microsoft Windows Hyper-V.

**Is there a fix for CVE-2026-83839?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-83839 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-83839?** Check whether you run Microsoft Windows Hyper-V. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A time-of-check time-of-use (toctou) race condition in Windows Hyper-V allows an authorized attacker with local access to elevate privileges. The vulnerability exists in Hyper-V's access control checks, where a race condition between permission validation and resource access can be exploited to bypass security restrictions and gain system-level privileges.

## Affected products

- Microsoft Windows Hyper-V

## Timeline

- 2026-10-13: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83839](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83839)

## Related threats

- [Microsoft Windows Hyper-V null pointer dereference DoS](https://junglewise.ai/threats/cve-2026-96965-null-pointer-dereference-in-windows-hyper-v-allows-an-authorized)
- [Microsoft Windows Hyper-V certificate validation bypass](https://junglewise.ai/threats/cve-2026-95910-improper-certificate-validation-in-windows-hyper-v-allows-an)
- [Microsoft Windows Hyper-V uninitialized resource privilege escalation](https://junglewise.ai/threats/cve-2026-119960-use-of-uninitialized-resource-in-windows-hyper-v-allows-an)
- [Windows Hyper-V access control spoofing vulnerability](https://junglewise.ai/threats/cve-2026-119959-improper-access-control-in-windows-hyper-v-allows-an-authorized)
- [Windows Hyper-V use-after-free privilege elevation](https://junglewise.ai/threats/cve-2026-119826-use-after-free-in-windows-hyper-v-allows-an-authorized-attacker)