🛡️ CVE-2026-42904 — windows-10-21h2

🔴 CVSS 9.6 — Critical ✅ No Known Exploit CWE-122 NVD
9.6
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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

How this vulnerability can be exploited

This issue can be reached from an adjacent network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is changed, meaning a successful attack can affect components beyond the vulnerable one. Rated impact: confidentiality high, integrity high, availability high.

Weakness class

CVE-2026-42904 is classified as CWE-122: Heap-based Buffer Overflow. A write past the end of a heap allocation corrupts allocator metadata or neighbouring objects.

Affected software and timeline

Affected software: unknown, windows-10-21h2 (fixed in 10.0.19044.7417), windows-10-22h2 (fixed in 10.0.19045.7417), windows-11-23h2 (fixed in 10.0.22631.7219), windows-11-24h2 (fixed in 10.0.26100.8655), windows-11-25h2 (fixed in 10.0.26200.8655), windows-11-26h1 (fixed in 10.0.28000.2269), windows-server-2022 (fixed in 10.0.20348.5256) and windows-server-2025 (fixed in 10.0.26100.32995). Published on 9 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

msrc.microsoft.com

Details

Severity CRITICAL
CVSS Score 9.6
CVSS Vector CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CWE CWE-122
Public Exploit ✅ No
Source NVD
Published 2026-06-09
Updated 2026-08-11
Modified 2026-06-09
Fix URL N/A

Affected Packages

Software From version Fixed in
unknown
windows-10-21h2 10.0.19044.7417
windows-10-22h2 10.0.19045.7417
windows-11-23h2 10.0.22631.7219
windows-11-24h2 10.0.26100.8655
windows-11-25h2 10.0.26200.8655
windows-11-26h1 10.0.28000.2269
windows-server-2022 10.0.20348.5256
windows-server-2025 10.0.26100.32995

Similar Threats

Exploit Protection

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