CVE-2026-77505: Windows DNS Server Remote Code Execution Vulnerability

Overview

Severity

High (CVSS 8.1)

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Category

Remote Code Execution

Exploit Status

Not Exploited

Exploitation Likelihood

Less Likely

Patch Tuesday

2026-Sep

Released

2026-09-08

Description

Use after free in DNS Server allows an unauthorized attacker to execute code over a network.

FAQ

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.

Affected Products (16)

Windows

• Windows 10 Version 1809 for 32-bit Systems
• Windows 10 Version 1809 for x64-based Systems
• Windows Server 2019
• Windows Server 2019 (Server Core installation)
• Windows Server 2022
• Windows Server 2022 (Server Core installation)
• Windows Server 2025 (Server Core installation)
• Windows Server 2025
• Windows 10 Version 1607 for 32-bit Systems
• Windows 10 Version 1607 for x64-based Systems
• Windows Server 2016
• Windows Server 2016 (Server Core installation)

ESU

• Windows Server 2012
• Windows Server 2012 (Server Core installation)
• Windows Server 2012 R2
• Windows Server 2012 R2 (Server Core installation)

Security Updates (6)

• 5122876
• 5122882
• 5122871
• 5123099
• 5123065
• 5123066

Acknowledgments

<a href="https://x.com/dark_puzzle">Souhail Hammou</a>

Revision History

• 2026-09-08: Information published.