CVE-2026-70225 in Windows
Summary
by MITRE • 10/14/2026
Access of resource using incompatible type ('type confusion') in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified as a type confusion flaw within the Windows Ancillary Function Driver for WinSock represents a critical security risk that undermines the integrity of privilege boundaries on affected systems. This specific component, often referred to by its driver file name afwpkt.sys or similar variants depending on the version, serves as an intermediary layer in the network stack architecture, facilitating communication between user-mode applications and kernel-mode drivers via Windows Sockets 2 (WinSock) APIs. The core technical flaw stems from improper handling of data types during resource access operations. Specifically, when processing certain IOCTL requests or internal function calls, the driver fails to strictly validate that the input parameters match the expected memory layout and type definitions. This lack of rigorous type checking allows an attacker who has already achieved local execution privileges within a lower-privileged context to craft malicious inputs that exploit this discrepancy. By supplying data structures with mismatched types, the attacker can manipulate internal pointers or state variables in ways that were not intended by the developers, leading to what is known as a type confusion error where the system interprets one data structure as another of an incompatible size or format.
From a technical perspective, this vulnerability falls squarely under the Common Weakness Enumeration category CWE-843, which addresses access using incorrect types without proper validation. The exploitation mechanism typically involves constructing a specially crafted network packet or IOCTL request that triggers the type confusion within the kernel space. Because the Windows networking stack operates with high privileges in the kernel mode, successfully exploiting this flaw allows an attacker to bypass standard security checks and execute arbitrary code with SYSTEM-level permissions. This effectively results in local privilege escalation, transforming a low-privileged user account into one with full administrative control over the operating system. The impact is severe because it compromises the fundamental trust model of Windows, allowing malware or malicious insiders to install persistent backdoors, steal sensitive data, disable security software, and move laterally across networked environments without detection by standard endpoint protection mechanisms that rely on privilege boundaries for containment.
In terms of threat modeling and industry standards, this vulnerability aligns with MITRE ATT&CK techniques related to Privilege Escalation via Exploitation of Local Security Authority Subsystem Service (LSASS) or general kernel exploitation patterns such as T1068 Exploitation for Privilege Escalation. The attack vector is classified as local, requiring the attacker to have some form of initial access, which limits its direct remote exploitability but increases its relevance in scenarios involving phishing, physical access, or compromised low-privilege accounts within an enterprise network. Defense-in-depth strategies are essential here since type confusion vulnerabilities often require precise memory layout knowledge and timing attacks to achieve reliable exploitation. However, the mere existence of such a flaw indicates a significant gap in input validation logic within critical system components.
Mitigation for this vulnerability primarily relies on applying the latest security patches released by Microsoft through Windows Update or manual installation of specific cumulative updates that address the afwpkt.sys driver flaws. Organizations should prioritize patching systems where users have local access, particularly servers and workstations handling sensitive data. Beyond patching, implementing strict application control policies using tools like AppLocker or Windows Defender Application Control can prevent unauthorized executables from running, thereby reducing the attack surface for initial compromise that leads to this escalation. Additionally, enabling Kernel DMA Protection on supported hardware platforms provides an additional layer of defense against memory corruption attacks by restricting direct memory access devices from accessing kernel memory without explicit permission. Regular auditing of system logs for unusual IOCTL activity and monitoring for anomalies in network stack behavior can also aid in early detection of exploitation attempts before full privilege escalation occurs.