PatchTheCVECVE-2026-83839: Time-of-check time-of-use (toctou) race condition in Windows Hyper-V allows an authorized attacker to elevate
CVE-2026-83839 is a high-severity flaw (CVSS 7.0) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Time-of-check time-of-use (toctou) race condition in Windows Hyper-V allows an authorized attacker to elevate privileges locally.
Why this priority
- High severity
- On your watchlist
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 7.0 (High) |
| Attack vector | Local |
| Attack complexity | High |
| Privileges needed | Low |
| User interaction | None |
| EPSS exploit chance | 0.2% (top 88%) |
| CISA exploited list | No |
| Weakness | CWE-367 |
| Published | 2026-10-13 |
| Last modified | 2026-10-16 |
Last updated 2026-10-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Timeline
- Published CVE record published
- Updated Record last modified
Advisories and coverage
Official advisories
- Microsoft MSRC Update Guide: CVE-2026-83839 Windows Hyper-V Elevation of Privilege Vulnerability 2026-10-20
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-83839?
No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.
Is CVE-2026-83839 being exploited?
CVE-2026-83839 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-83839 affect?
CVE-2026-83839 affects affected software. Severity is high (CVSS 7.0). Time-of-check time-of-use (toctou) race condition in Windows Hyper-V allows an authorized attacker to elevate privileges locally.
How urgent is CVE-2026-83839?
Priority 33/100. High severity; On your watchlist
Software pages
Windows vulnerabilities · Hyper-V vulnerabilities