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major vulnerability· requires attention

Affects Microsoft Hyper‑V, a widely used enterprise hypervisor; impact on virtualized infrastructure could be organization‑wide.

Infrastructure

CVE-2026-83728

8.8
High
EPSS 0.24%Patch availableOct 14, 2026

Authenticated local input validation flaw in Hyper‑V allows spoofing of Hyper‑V components.

common questions

Is CVE-2026-83728 being exploited?

Not confirmed. CVE-2026-83728 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.24% probability of exploitation in the next 30 days.

How severe is CVE-2026-83728?

CVE-2026-83728 is rated High with a CVSS score of 8.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2026-83728?

Yes. A fix has been recorded for CVE-2026-83728. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2026-83728 affect?

CVE-2026-83728 affects Microsoft Hyper-V (Windows host hypervisor). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

What should I do about CVE-2026-83728?

Install Microsoft Hyper‑V updates; restrict local Hyper‑V access and monitor logs.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

executive summary
technical analysis
affected
Microsoft Hyper-V (Windows host hypervisor)
impact

Authenticated local attacker can spoof Hyper‑V inputs/components to impersonate services, enabling control bypass, misconfiguration or privilege escalation.

action required

Patch when possible

affected versions
Microsoft Windows 10 Version 1607
  • affected>= 10.0.14393.0 and < 10.0.14393.9612
Microsoft Windows 10 Version 1809
  • affected>= 10.0.17763.0 and < 10.0.17763.9376
Microsoft Windows 10 Version 21H2
  • affected>= 10.0.19044.0 and < 10.0.19044.7807
Microsoft Windows 10 Version 22H2
  • affected>= 10.0.19045.0 and < 10.0.19044.7807
Microsoft Windows 11 version 23H2
  • affected>= 10.0.22631.0 and < 10.0.22631.7652
Microsoft Windows 11 Version 23H2
  • affected>= 10.0.22631.0 and < 10.0.22631.7652
Microsoft Windows 11 Version 24H2
  • affected>= 10.0.26100.0 and < 10.0.26100.9711
Microsoft Windows 11 Version 25H2
  • affected>= 10.0.26200.0 and < 10.0.26200.9711
Microsoft Windows 11 version 26H1
  • affected>= 10.0.28000.0 and < 10.0.28000.3231
Microsoft Windows 11 Version 26H2
  • affected>= 10.0.26300.0 and < 10.0.26300.9711
Microsoft Windows Server 2012
  • affected>= 6.2.9200.0 and < 6.2.9200.26434
Microsoft Windows Server 2012 R2
  • affected>= 6.3.9600.0 and < 6.3.9600.23470
Microsoft Windows Server 2012 R2 (Server Core installation)
  • affected>= 6.3.9600.0 and < 6.3.9600.23470
Microsoft Windows Server 2012 (Server Core installation)
  • affected>= 6.2.9200.0 and < 6.2.9200.26434
Microsoft Windows Server 2016
  • affected>= 10.0.14393.0 and < 10.0.14393.9612
Microsoft Windows Server 2016 (Server Core installation)
  • affected>= 10.0.14393.0 and < 10.0.14393.9612
Microsoft Windows Server 2019
  • affected>= 10.0.17763.0 and < 10.0.17763.9376
Microsoft Windows Server 2019 (Server Core installation)
  • affected>= 10.0.17763.0 and < 10.0.17763.9376
Microsoft Windows Server 2022
  • affected>= 10.0.20348.0 and < 10.0.20348.5761
Microsoft Windows Server 2025
  • affected>= 10.0.26100.0 and < 10.0.26100.33650
Microsoft Windows Server 2025 (Server Core installation)
  • affected>= 10.0.26100.0 and < 10.0.26100.33650

As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.

how to fix
Remediation steps are tailored for users whose stack is affected. Add this technology to your stack to see the fix checklist.
references
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