CVE-2026-42904 Windows TCP/IP Elevation of Privilege Vulnerability
Heap-based buffer overflow in Windows TCP/IP allows adjacent network attackers to elevate privileges.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-42904?
CVE-2026-42904 is a critical memory corruption vulnerability in Microsoft Windows 10 21h2, published on 9 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Heap-based buffer overflow in Windows TCP/IP allows an unauthorized attacker to elevate privileges over an adjacent network.
Weakness: CWE-122
Which versions are affected by CVE-2026-42904?
It affects 8 products.
Products include Microsoft Windows 10 21h2, Microsoft Windows 10 22h2, Microsoft Windows 11 23h2, Microsoft Windows 11 24h2, Microsoft Windows 11 25h2, Microsoft Windows 11 26h1 and 2 more.
How do I fix CVE-2026-42904?
No fix has been published for CVE-2026-42904 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-42904 being exploited?
There is no known exploitation of CVE-2026-42904 in the wild and no public exploit code.
Other vulnerabilities in Microsoft Windows 10 21h2
- CVE-2025-21333 Microsoft Windows Hyper-V NT Kernel Integration VSP Heap-based Buffer Overflow
- CVE-2025-21334 Microsoft Windows Hyper-V NT Kernel Integration VSP Use-After-Free
- CVE-2025-21335 Microsoft Windows Hyper-V NT Kernel Integration VSP Use-After-Free
- CVE-2026-105733 Windows Hyper-V Remote Code Execution Vulnerability
- CVE-2026-69945 Windows AppX Deployment Extensions Elevation of Privilege Vulnerability
Sources
Also known as GHSA-3f78-xrf3-9xc8.