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CVE-2026-45641 Microsoft CVE debrief

CVE-2026-45641 is a HIGH severity vulnerability in Windows Hyper-V that allows an unauthorized attacker to execute code locally. The vulnerability has a CVSS score of 8.4 and was published on 2026-06-09T17:17:31.100Z. The vulnerability was modified on 2026-06-11T17:42:07.063Z.

Vendor
Microsoft
Product
Windows 10 Version 21H2
CVSS
HIGH 8.4
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-09
Original CVE updated
2026-07-09
Advisory published
2026-06-09
Advisory updated
2026-07-09

Who should care

Administrators and users of Windows Hyper-V are advised to take immediate action to mitigate this vulnerability.

Technical summary

The vulnerability is an out-of-bounds read in Windows Hyper-V, which allows an unauthorized attacker to execute code locally. The vulnerability affects multiple versions of Windows, including Windows 10, Windows 11, and Windows Server.

Defensive priority

HIGH

Recommended defensive actions

  • Apply patches from Microsoft as soon as possible.
  • Refer to [ref-4](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45641) for mitigation or vendor reference.

Evidence notes

The vulnerability is analyzed and has a CVSS vector of CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-45641 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-45641

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-45641 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-45641

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.