Summary
Impact: Remote Code Execution. Microsoft rating: Critical. Not known to be exploited — Exploitation Less Likely. Customer action: Required.
Details
According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability?
Successful exploitation of this vulnerability requires an attacker to win a race condition.
How could an attacker exploit this vulnerability?
An unauthenticated attacker could send DNS queries to a Windows DNS Server that is configured with a server-level DNS plug-in, attempting to win a timing-dependent race condition in the server's record-handling logic. Successful exploitation could allow the attacker to execute code on the DNS server with SYSTEM privileges. Network access is required; authentication and user interaction are not required.
Security updates
10.0.17763.9245 — https://support.microsoft.com/help/5122876
10.0.20348.5622 — https://support.microsoft.com/help/5122882
10.0.26100.33438 — https://support.microsoft.com/help/5122871
10.0.14393.9512 — https://support.microsoft.com/help/5123099
6.2.9200.26349 — https://support.microsoft.com/help/5123065
6.3.9600.23398 — https://support.microsoft.com/help/5123066
Vulnerabilities 1
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High 8.1
Windows DNS Server Remote Code Execution Vulnerability
Use after free in DNS Server allows an unauthorized attacker to execute code over a network.
Revision history
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#1
Information published.
References
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CVE-2026-77505 Windows DNS Server Remote Code Execution Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-77505
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Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
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Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
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Common Vulnerability Scoring System
https://www.first.org/cvss