CVE-2026-42915 — Microsoft Windows VMSwitch Denial of Service Vulnerability

Executive Summary

Incorrect calculation of buffer size in Windows VMSwitch allows an authorized attacker to deny service locally.

Overview

5.7

CVSS MEDIUM

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Denial of Service

Released Jun 9 2026

Last Updated Jun 9 2026

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.00351 — 0.26791 percentile

NVD CVSS 5.7 MEDIUM — differs from MSRC

CVSS Vector

CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C

ATTACK VECTOR

Adjacent_network

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

None

INTEGRITY

None

AVAILABILITY

High

EXPLOIT CODE MATURITY

Unproven

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 4.8

EPSS Score

0.00351

probability of exploitation in the next 30 days

0.26791 percentile - updated 2026-06-21

View on FIRST.org

Affected Products

18 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 21H2 for 32-bit Systems	`5094127 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 21H2 for ARM64-based Systems	`5094127 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 21H2 for x64-based Systems	`5094127 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 22H2 for 32-bit Systems	`5094127 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 22H2 for ARM64-based Systems	`5094127 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 22H2 for x64-based Systems	`5094127 (Security Update)`	Important	Denial of Service	Yes
Windows 11 Version 23H2 for ARM64-based Systems	`5093998 (Security Update)`	Important	Denial of Service	Yes
Windows 11 Version 23H2 for x64-based Systems	`5093998 (Security Update)`	Important	Denial of Service	Yes
Windows 11 Version 24H2 for ARM64-based Systems	`5094126 (Security Update)`	Important	Denial of Service	Yes
Windows 11 Version 24H2 for x64-based Systems	`5094126 (Security Update)`	Important	Denial of Service	Yes
Windows 11 Version 25H2 for ARM64-based Systems	`5094126 (Security Update)`	Important	Denial of Service	Yes
Windows 11 Version 25H2 for x64-based Systems	`5094126 (Security Update)`	Important	Denial of Service	Yes
Windows 11 Version 26H1 for ARM64-based Systems	`5095051 (Security Update)`	Important	Denial of Service	Yes
Windows 11 version 26H1 for x64-based Systems	`5095051 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2022	`5094128 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2022 (Server Core installation)	`5094128 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2025	`5094125 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2025 (Server Core installation)	`5094125 (Security Update)`	Important	Denial of Service	Yes

Patches

6 patches

Article	Type	Restart
`5094127`	Security Update	Yes
`5093998`	Security Update	Yes
`5094126`	Security Update	Yes
`5095051`	Security Update	Yes
`5094128`	Security Update	Yes
`5094125`	Security Update	Yes

Known Exploits

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

Linzishan & Anemone & Zhiniang Peng (HUST), Anonymous, Calif.io and Milad Nasr (Anthropic) with Claude with Calif.io and Anthropic, Wongi Lee, Jungwoo Lee

References

MSRC Advisory MITRE NVD