Use After Free in Windows Ancillary Function Driver for WinSock

Executive Summary

CVE-2026-50312 is a use-after-free vulnerability in the Windows Ancillary Function Driver for WinSock (AFD). This flaw occurs when the driver improperly handles memory after it has been freed, allowing an attacker to exploit the dangling pointer to execute arbitrary code or manipulate system behavior.

An authorized attacker with local access to the system can exploit this vulnerability to elevate their privileges. This means the attacker could gain higher-level permissions, such as administrative rights, on the affected Windows system.

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Detection Guidance

The provided context does not include specific detection methods or commands for identifying the presence of CVE-2026-50312 on a network or system. Detection typically involves checking for vulnerable versions of the Windows Ancillary Function Driver for WinSock or applying security updates provided by Microsoft.

To verify if your system is vulnerable, you may check the installed updates or patches related to this CVE via Windows Update history or by using system management tools. Microsoft may also provide guidance in their security update documentation.

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Impact Analysis

If exploited, this vulnerability could have several impacts on you or your organization:

• Privilege escalation: An attacker with local access could gain elevated privileges, allowing them to perform actions they would not normally be authorized to do, such as installing software, accessing restricted data, or modifying system configurations.
• System compromise: With elevated privileges, an attacker could take full control of the affected system, potentially leading to data theft, system damage, or further lateral movement within a network.
• Security bypass: The vulnerability could be used to bypass security mechanisms that rely on proper privilege separation, undermining the overall security posture of the system.

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Compliance Impact

This vulnerability could impact compliance with several common standards and regulations in the following ways:

• GDPR (General Data Protection Regulation): If the vulnerability leads to unauthorized access to personal data, it could result in a data breach. Under GDPR, organizations must implement appropriate security measures to protect personal data. Failure to patch this vulnerability or mitigate its risks could be seen as a violation of Article 32 (security of processing), leading to potential fines or legal consequences.
• HIPAA (Health Insurance Portability and Accountability Act): For organizations handling protected health information (PHI), this vulnerability could lead to unauthorized access or disclosure of PHI. HIPAA requires covered entities to implement safeguards to protect PHI, and a breach resulting from this vulnerability could violate the Security Rule, leading to penalties.
• Other standards (e.g., ISO 27001, NIST): Many compliance frameworks require organizations to maintain secure systems and address vulnerabilities promptly. Failure to patch or mitigate this vulnerability could result in non-compliance with requirements related to vulnerability management, access control, and system integrity.

To maintain compliance, organizations should apply the necessary patches or mitigations provided by Microsoft to address this vulnerability.

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Mitigation Strategies

To mitigate CVE-2026-50312, apply the security update provided by Microsoft as soon as possible. The update addresses the use-after-free vulnerability in the Windows Ancillary Function Driver for WinSock.

• Visit the Microsoft Update Guide for CVE-2026-50312 to download and install the latest patch.
• Ensure all systems running affected versions of Windows are updated to the latest secure version.
• Restrict local access to authorized users only, as the vulnerability requires local access to exploit.

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