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