CVE-2026-45596 in Windows
Summary
by MITRE • 06/09/2026
Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 09/20/2026
The vulnerability under discussion represents a use-after-free condition within the Windows Ancillary Function Driver for WinSock component, which serves as a critical system interface for network operations. This flaw exists in the way the driver handles memory management during socket operations, specifically when processing certain network requests that involve ancillary data structures. The issue stems from improper memory deallocation practices where freed memory blocks are still referenced or accessed by subsequent operations, creating a scenario where an attacker can manipulate the system's memory state to execute arbitrary code with elevated privileges.
The technical implementation of this vulnerability involves the exploitation of memory management inconsistencies within the winsock2.dll and related kernel components that handle network communication. When legitimate network operations occur through the ancillary function driver, the system allocates memory for processing network data, but fails to properly invalidate references to that memory before it gets freed. An authorized local user can leverage this condition by crafting specific network requests that trigger the memory deallocation sequence, then immediately attempting to access the freed memory locations through manipulated data structures. This creates a race condition where the attacker can inject malicious code into the freed memory space, effectively bypassing standard security boundaries and gaining elevated privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation as it represents a fundamental weakness in the Windows kernel's memory management subsystem that affects all versions of Windows that utilize the affected ancillary function driver. The attack vector requires local system access, meaning that an attacker must already have valid user credentials to exploit this vulnerability, but the privilege escalation to SYSTEM level provides complete control over the affected system. This vulnerability is particularly concerning because it operates within the kernel space of the operating system, making detection and prevention extremely challenging. The exploitation process typically involves crafting specific network packets or socket operations that trigger the memory corruption, followed by a carefully timed execution sequence to leverage the freed memory for code injection.
Mitigation strategies for this vulnerability involve immediate patch deployment through Microsoft's regular security updates, which address the memory management flaws in the ancillary function driver component. System administrators should implement the principle of least privilege and ensure that only necessary network services are running on affected systems. The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions, and represents a common attack pattern that falls under the MITRE ATT&CK framework's privilege escalation techniques. Organizations should also consider implementing network segmentation and monitoring for unusual network activity that might indicate exploitation attempts, while maintaining comprehensive system logs for forensic analysis. The vulnerability demonstrates the critical importance of proper memory management in kernel-level components and highlights the need for thorough security testing of system drivers that handle network communications.