CVE-2026-42904

Windows TCP/IP Elevation of Privilege Vulnerability

CVE-2026-42904 is fixed in 18 products on 1 platform, first by KB5094127, released June 9, 2026. It is not reported as exploited. Patch Radar priority: High.

High

CVSS

9.6

Important

Exploitation

None reported

Exploitation Unlikely

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0044

38th percentile

<p>Heap-based buffer overflow in Windows TCP/IP allows an unauthorized attacker to elevate privileges over an adjacent network.</p>

Where it's fixed

Product	Fixed in	Fix	Released
Microsoft
Windows 10 Version 21H2 for 32-bit Systems		KB5094127	Jun 9, 2026
Windows 10 Version 21H2 for ARM64-based Systems		KB5094127	Jun 9, 2026
Windows 10 Version 21H2 for x64-based Systems		KB5094127	Jun 9, 2026
Windows 10 Version 22H2 for 32-bit Systems		KB5094127	Jun 9, 2026
Windows 10 Version 22H2 for ARM64-based Systems		KB5094127	Jun 9, 2026
Windows 10 Version 22H2 for x64-based Systems		KB5094127	Jun 9, 2026
Windows 11 Version 23H2 for ARM64-based Systems	22631.7219	KB5093998	Jun 9, 2026
Windows 11 Version 23H2 for x64-based Systems	22631.7219	KB5093998	Jun 9, 2026
Windows 11 Version 24H2 for ARM64-based Systems		KB5094126	Jun 9, 2026
Windows 11 Version 24H2 for x64-based Systems		KB5094126	Jun 9, 2026
Windows 11 Version 25H2 for ARM64-based Systems		KB5094126	Jun 9, 2026
Windows 11 Version 25H2 for x64-based Systems		KB5094126	Jun 9, 2026
Windows 11 Version 26H1 for ARM64-based Systems	28000.2269	KB5095051	Jun 9, 2026
Windows 11 version 26H1 for x64-based Systems	28000.2269	KB5095051	Jun 9, 2026
Windows Server 2022	20348.5256	KB5094128	Jun 9, 2026
Windows Server 2022 (Server Core installation)	20348.5256	KB5094128	Jun 9, 2026
Windows Server 2025	26100.32995	KB5094125	Jun 9, 2026
Windows Server 2025 (Server Core installation)	26100.32995	KB5094125	Jun 9, 2026

Details

Published
June 9, 2026
Weakness
Heap-based Buffer Overflow
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42904

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