Heap-based Buffer Overflow in Active Directory Domain Services

Executive Summary

CVE-2026-49164 is a heap-based buffer overflow vulnerability in Microsoft Active Directory Domain Services. This flaw allows an unauthorized attacker to execute arbitrary code over a network without requiring any privileges or user interaction.

A heap-based buffer overflow occurs when a program writes more data to a buffer than it can hold, corrupting memory. In this case, the vulnerability exists in Active Directory Domain Services, which is a critical component for managing network resources and authentication in Windows environments.

The CVSS v3.1 score for this vulnerability is 8.1, indicating a high severity. The vector AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H means the attack can be carried out over a network (AV:N), requires some complexity (AC:H), does not need privileges (PR:N), does not require user interaction (UI:N), and can result in high impacts to confidentiality, integrity, and availability (C:H/I:H/A:H).

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Detection Guidance

The provided context does not include specific detection methods or commands for identifying CVE-2026-49164 on a network or system. Detection typically involves checking for vulnerable versions of Active Directory Domain Services or using security tools to monitor for anomalous network traffic or exploitation attempts.

For accurate detection guidance, refer to Microsoft's official documentation or security advisories, which may provide updated tools or scripts to identify this vulnerability.

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Impact Analysis

This vulnerability can have severe impacts if exploited, including:

• Remote code execution: An attacker could execute malicious code on affected systems, potentially taking full control of the Active Directory Domain Services.
• Unauthorized access: The attacker could gain access to sensitive data, user credentials, or other critical network resources managed by Active Directory.
• Network compromise: Since Active Directory is often used for authentication and authorization, an attacker could move laterally across the network, compromising additional systems.
• Service disruption: The attacker could disrupt services relying on Active Directory, leading to downtime or operational failures.

Given the high severity and the potential for remote exploitation, this vulnerability poses a significant risk to organizations using Active Directory Domain Services.

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Compliance Impact

This vulnerability can impact compliance with several common standards and regulations, including:

• GDPR (General Data Protection Regulation): If the vulnerability leads to unauthorized access or disclosure of personal data, it could result in a violation of GDPR. Organizations may face fines, legal action, or reputational damage for failing to protect personal data adequately.
• HIPAA (Health Insurance Portability and Accountability Act): For organizations handling protected health information (PHI), exploitation of this vulnerability could lead to unauthorized access to PHI, resulting in HIPAA violations. This could include penalties and mandatory corrective actions.
• ISO 27001: This standard requires organizations to implement controls to manage information security risks. Failure to address this vulnerability could indicate non-compliance with ISO 27001, particularly in areas related to access control, network security, and incident management.
• NIST Cybersecurity Framework: The vulnerability could affect compliance with the NIST framework, particularly the Identify, Protect, Detect, Respond, and Recover functions. Organizations may need to demonstrate they have taken steps to mitigate the risk.

To maintain compliance, organizations should promptly apply patches or mitigations provided by Microsoft and ensure their Active Directory environments are secured against this vulnerability.

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Mitigation Strategies

Immediate steps to mitigate CVE-2026-49164 include:

• Apply the latest security updates or patches provided by Microsoft for Active Directory Domain Services. Refer to the Microsoft Security Update Guide for the specific patch related to this CVE.
• Restrict network access to Active Directory Domain Services to trusted systems only, reducing the attack surface.
• Monitor network traffic for signs of exploitation attempts, such as unusual requests targeting Active Directory services.
• Review and enforce least-privilege access controls to limit the impact of potential exploitation.

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