CVE-2026-70205 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.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
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 driver, often referred to by its file name afwpkt.sys or similar variants depending on the version, serves as an intermediary between user-mode applications and kernel-mode network stack components. It facilitates various ancillary functions required for advanced networking features, including packet filtering, quality of service management, and other WinSock extensions. The core technical flaw lies in how this driver handles data types during resource access operations. Specifically, the software fails to properly validate or cast input parameters before using them to interact with internal structures or memory regions. This lack of rigorous type checking allows an attacker who has already gained local execution capabilities within a lower-privileged context to supply crafted inputs that cause the kernel to interpret data incorrectly.
From a technical perspective, this is classified as CWE-843, Access of Resource Using Incompatible Type, which falls under the broader category of memory corruption vulnerabilities often associated with improper type casting or interpretation in C/C++ based drivers. When an authorized attacker exploits this flaw, they can manipulate the kernel's understanding of data structures, leading to a state where the driver performs operations on incorrect memory addresses or executes code paths intended for different privilege levels. This mechanism effectively bypasses standard access control checks because the vulnerability exists within the trusted system boundary itself. The exploitation typically involves constructing specific network packets or API calls that trigger the type confusion scenario during processing by the afwpkt.sys module. By carefully crafting these inputs, an attacker can achieve arbitrary code execution in kernel space, which is the highest level of privilege on a Windows operating system.
The operational impact of this vulnerability is severe due to its potential for local privilege escalation. An attacker who successfully exploits this flaw gains SYSTEM-level access, equivalent to full administrative control over the compromised host. This grants unrestricted read and write access to all files, registry keys, and running processes. Furthermore, with kernel-mode execution rights, an attacker can install rootkits, disable security software such as antivirus or endpoint detection and response solutions, and create persistent backdoors that are difficult to detect through standard user-mode monitoring tools. The ability to escalate privileges locally means that even if initial access is limited to a low-privilege account, the threat actor can quickly expand their control over the entire system environment. This aligns with MITRE ATT&CK technique T1068, Exploitation for Privilege Escalation, specifically highlighting how vulnerabilities in kernel drivers are leveraged to move from user-level access to domain or local administrative dominance.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. The primary defense is the timely application of security updates provided by Microsoft that address this specific type confusion issue within the Ancillary Function Driver for WinSock. Organizations should prioritize deploying these patches across all endpoints, particularly those connected to sensitive networks or handling critical data. In environments where immediate patching is not feasible due to compatibility concerns, network segmentation and strict access controls can help limit the attack surface by preventing unauthorized users from gaining even initial local execution capabilities. Additionally, enabling advanced security features such as Kernel Patch Protection (PatchGuard) and memory integrity checks via Windows Defender Application Control or Hyper-V based Security can provide additional layers of defense against exploitation attempts that target kernel drivers. Regular auditing of driver signatures and enforcing strict code signing policies further reduces the risk of malicious or vulnerable third-party components interacting with critical system functions.