CVE-2026-78523: Windows DNS Server Denial of Service Vulnerability
Use after free in Windows DNS allows an unauthorized attacker to deny service over a network.
Other sources
Windows DNS Server Denial of Service Vulnerability
— Microsoft
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.2.9200.26349Patch KB5123065 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.3.9600.23397Patch KB5123066 - Upgrade
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Fixed in 10.0.17763.9245Patch KB5122876 - Upgrade
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Fixed in 10.0.14393.9512Patch KB5123099 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.26100.33438Patch KB5122871 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 10.0.20348.5622Patch KB5122882
Event History
Frequently Asked Questions
Which systems are exposed to this issue?
The affected software list includes Microsoft Windows 10 and Windows Server 2012, 2012 R2, 2016, 2019, 2022, and 2025. Exposure is relevant where the Windows DNS Server component is deployed and reachable over the network.
What does an attacker need to exploit the vulnerability?
The vulnerability can be exploited remotely over a network by an unauthorized attacker. No privileges or user interaction are required, although the attack complexity is rated high.
What is the likely impact of successful exploitation?
Successful exploitation can cause a denial of service affecting Windows DNS. The supplied metrics indicate availability impact only, with no stated confidentiality or integrity impact.