CVE-2026-78523 Windows DNS Server Denial of Service Vulnerability
An unauthorized attacker can cause a denial of service in Windows DNS Server via a use-after-free vulnerability.
- 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-2026-78523?
CVE-2026-78523 is a medium-severity use after free vulnerability in Microsoft Windows 10 1607, published on 8 Sep 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 DNS allows an unauthorized attacker to deny service over a network.
Weakness: CWE-416
Which versions are affected by CVE-2026-78523?
It affects 7 products.
Products include Microsoft Windows 10 1607, Microsoft Windows 10 1809, Microsoft Windows Server 2012, Microsoft Windows Server 2016, Microsoft Windows Server 2019, Microsoft Windows Server 2022 and 1 more.
How do I fix CVE-2026-78523?
No fix has been published for CVE-2026-78523 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-2026-78523 being exploited?
There is no known exploitation of CVE-2026-78523 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-288r-53p6-9f5p.