Use-after-free in Microsoft Windows and Windows Server - CVE-2026-77505
Published: September 9, 2026
Vulnerability identifier: #VU148184
CSH Severity: High
CVSS v4: 9.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-77505
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to use-after-free in the DNS Server record-handling logic when processing DNS queries. A remote attacker can send DNS queries and win a timing-dependent race condition to execute arbitrary code.
Only Windows DNS Server instances configured with a server-level DNS plug-in are vulnerable.
Affected software
Microsoft Windows
Windows Server
Windows Server
How to mitigate CVE-2026-77505
Install security update from vendor's website.
Microsoft Windows - addressed in versions 10 1607 10.0.14393.9512, 10 1809 10.0.17763.9245
Windows Server - addressed in versions 2012 R2 6.3.9600.23397, 2012 6.2.9200.26349, 2016 10.0.14393.9512, 2019 10.0.17763.9245, 2022 10.0.20348.5622, 2025 10.0.26100.33438
Windows Server - addressed in versions 2012 R2 6.3.9600.23397, 2012 6.2.9200.26349, 2016 10.0.14393.9512, 2019 10.0.17763.9245, 2022 10.0.20348.5622, 2025 10.0.26100.33438