Medium 5.5Published Jun 9, 2026

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

Updated under an hour ago (Oct 27, 2026, 5:40 AM ET)

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It affects Microsoft Windows 10 Version 21H2 and 7 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Microsoft Windows 10 Version 21H2

Exploited in the last 30 days

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

CVSS: 5.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C
Weakness (CWE): CWE-131
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: microsoft
NVD analysis: Modified
Record last updated: Sep 24, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Microsoft Windows 10 Version 21H2 microsoft:windows_10_21h2	from 10.0.19044.0 before 10.0.19044.7417	CNA record
Microsoft Windows 10 Version 22H2 microsoft:windows_10_22h2	from 10.0.19045.0 before 10.0.19045.7417	CNA record
Microsoft Windows 11 version 23H2 microsoft:windows_11_23h2	from 10.0.22631.0 before 10.0.22631.7219	CNA record
Microsoft Windows 11 Version 24H2 microsoft:windows_11_24h2	from 10.0.26100.0 before 10.0.26100.8655	CNA record
Microsoft Windows 11 Version 25H2 microsoft:windows_11_25h2	from 10.0.26200.0 before 10.0.26200.8655	CNA record
Microsoft Windows 11 version 26H1 microsoft:windows_11_26h1	from 10.0.28000.0 before 10.0.28000.2269	CNA record
Microsoft Windows Server 2022 microsoft:windows_server_2022 (from the name)	from 10.0.20348.0 before 10.0.20348.5256	CNA record
Microsoft Windows Server 2025 microsoft:windows_server_2025 (from the name)	from 10.0.26100.0 before 10.0.26100.32995	CNA record
microsoft windows_10_21h2 microsoft:windows_10_21h2	before 10.0.19044.7417; before 10.0.19044.7417; before 10.0.19044.7417	NVD
microsoft windows_10_22h2 microsoft:windows_10_22h2	before 10.0.19045.7417; before 10.0.19045.7417; before 10.0.19045.7417	NVD
1–10 of 16

References

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42915	vendor-advisory, patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.