CVE-2026-83667 in Windows
Summary
by MITRE • 10/14/2026
Out-of-bounds read in Active Directory Domain Services allows an authorized attacker to deny service over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified as an out-of-bounds read within Microsoft Active Directory Domain Services represents a critical security flaw that impacts the integrity and availability of directory services infrastructure. This specific defect occurs when the domain controller processes certain requests, leading it to access memory locations beyond the intended buffer boundaries. While traditional out-of-bounds reads are often associated with information disclosure or potential code execution in other contexts, this particular instance is characterized by its ability to trigger a denial of service condition. The flaw allows an authenticated attacker who has valid credentials within the domain to exploit this memory handling error remotely over the network. By crafting specific malicious requests that trigger the out-of-bounds access, the attacker can cause the affected component or the entire domain controller process to crash or become unresponsive, thereby disrupting directory services for all users and systems relying on authentication and authorization from that server.
From a technical perspective, this vulnerability falls under the category of CWE-125, which defines out-of-bounds read vulnerabilities where software reads data past the end or before the beginning of the intended buffer. In the context of Active Directory Domain Services, such memory corruption typically results in an exception being thrown by the operating system when invalid memory is accessed. Because domain controllers are central to enterprise identity management, their unavailability has severe operational consequences. The immediate impact includes the inability for users to log on to network resources, failure of replication between domain controllers, and potential disruption of group policy application. This effectively creates a single point of failure that can paralyze an organization's IT operations until the affected service is restored or patched.
The exploitation vector requires authentication, which aligns with MITRE ATT&CK technique T1078, Valid Accounts. An attacker must possess legitimate credentials to interact with the domain controller and send the malformed requests necessary to trigger the vulnerability. This requirement limits the attack surface compared to unauthenticated remote code execution flaws but still poses a significant risk for insider threats or compromised accounts that have been granted excessive privileges. The ability to deny service remotely means that an adversary can disrupt business continuity without needing physical access or complex social engineering tactics beyond initial credential theft.
Mitigation strategies primarily involve applying the latest security updates provided by Microsoft, which address the memory handling logic within Active Directory Domain Services. Organizations should prioritize patching domain controllers in their environments, particularly those exposed to internal networks where compromised accounts might exist. Additionally, implementing strict access controls and monitoring for unusual authentication patterns can help detect potential exploitation attempts before they cause service disruption. Network segmentation that limits direct communication between potentially compromised endpoints and critical directory services infrastructure can also reduce the risk of successful exploitation. Regular auditing of privileged account usage and enforcing least privilege principles are essential defensive measures to minimize the likelihood of an attacker obtaining the necessary credentials to trigger this vulnerability.