CVE-2026-40406 Windows TCP/IP Information Disclosure Vulnerability
An unauthorized attacker can disclose information over the network via a use-after-free flaw in the Windows TCP/IP stack.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-40406?
CVE-2026-40406 is a high-severity use after free vulnerability in Microsoft Windows 10 1607, published on 12 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Use after free in Windows TCP/IP allows an unauthorized attacker to disclose information over a network.
Weakness: CWE-416
Which versions are affected by CVE-2026-40406?
It affects 14 products.
Products include Microsoft Windows 10 1607, Microsoft Windows 10 1809, Microsoft Windows 10 21h2, Microsoft Windows 10 22h2, Microsoft Windows 11 23h2, Microsoft Windows 11 24h2 and 8 more.
How do I fix CVE-2026-40406?
No fix has been published for CVE-2026-40406 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-40406 being exploited?
There is no known exploitation of CVE-2026-40406 in the wild and no public exploit code.
Other vulnerabilities in Microsoft Windows 10 1607
- CVE-2026-33824 Microsoft Internet Key Exchange (IKE) Service Extensions Double Free
- CVE-2026-21510 Microsoft Windows Shell Protection Mechanism Failure
- CVE-2026-21513 Microsoft MSHTML Framework Protection Mechanism Failure
- CVE-2023-32049 Microsoft Windows Defender SmartScreen Security Feature Bypass
- CVE-2023-29360 Microsoft Streaming Service Untrusted Pointer Dereference
Sources
Also known as GHSA-37x6-37vf-qf3r.