CVE-2026-62817 in Windows
Summary
by MITRE • 08/11/2026
Out-of-bounds write in Windows DNS allows an unauthorized attacker to execute code over an adjacent network.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability represents a critical out-of-bounds write flaw in the Windows Domain Name System (DNS) server implementation that enables remote code execution when exploited by attackers within an adjacent network segment. The technical nature of this vulnerability stems from insufficient input validation and boundary checking within the DNS server's handling of certain query responses, allowing maliciously crafted packets to overwrite memory regions beyond allocated buffers. Such out-of-bounds writes typically occur when the DNS server processes malformed or specially constructed DNS responses without proper bounds verification, creating opportunities for attackers to inject arbitrary code into the target system's memory space.
The operational impact of this vulnerability extends significantly within network environments where Windows DNS servers operate as primary infrastructure components. Attackers leveraging this flaw can execute arbitrary code with the privileges of the DNS server process, typically running with high system privileges on domain controllers or authoritative DNS servers. The adjacent network requirement means that exploitation is limited to attackers who can directly communicate with the target DNS server, either through local network access or by compromising intermediate network devices. This constraint reduces the attack surface compared to fully remote vulnerabilities but still presents severe risks when attackers gain access to network segments containing critical DNS infrastructure.
This vulnerability aligns with CWE-787 Out-of-bounds Write and follows patterns commonly associated with memory corruption flaws that enable privilege escalation and code execution. The attack vector typically involves sending specially crafted DNS response packets that trigger the buffer overflow condition during DNS server processing, potentially allowing attackers to manipulate program execution flow through stack or heap corruption techniques. Security researchers have noted that such vulnerabilities often map to ATT&CK technique T1059 Command and Scripting Interpreter when exploited for lateral movement or persistence within compromised networks.
Mitigation strategies should prioritize immediate patch deployment from Microsoft's security updates, as the vulnerability affects multiple Windows server versions including 2016, 2019, and 2022. Network segmentation practices should be enhanced to limit direct DNS server access, while implementing proper firewall rules to restrict DNS traffic to authorized network segments only. Additional protective measures include monitoring for unusual DNS query patterns, implementing DNS security extensions, and deploying intrusion detection systems that can identify potential exploitation attempts through malformed DNS responses. Organizations should also consider network access control lists and mandatory access controls to reduce the attack surface of critical DNS infrastructure components.