CVE-2026-70245 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 involves a critical logic error within the Windows Ancillary Function Driver for WinSock, specifically manifesting as a type confusion flaw that permits local privilege escalation. This component of the operating system is responsible for managing network-related auxiliary functions and interfaces with various protocol drivers to facilitate communication between user-mode applications and kernel-mode networking stacks. The core technical issue arises when the driver fails to properly validate or cast data types during resource access operations, leading to a scenario where an object is treated as having a different type than its actual definition in memory. This misalignment allows for improper handling of internal structures, potentially resulting in arbitrary code execution within the context of the currently logged-in user if exploited through standard application boundaries, but more critically, it provides a pathway for attackers to manipulate kernel-level data structures when interacting with specific privileged interfaces or drivers that rely on this ancillary function.
From a technical perspective, type confusion vulnerabilities are particularly dangerous because they bypass many traditional memory safety checks by exploiting the assumptions made by compiled code regarding object layouts and method dispatching. In the context of Windows driver development, such errors often stem from insufficient boundary checking or incorrect casting during pointer arithmetic operations. When an authorized attacker interacts with this vulnerable component, they can craft specific inputs that trigger the type mismatch in a controlled manner. This control allows them to overwrite critical kernel pointers or execute arbitrary instructions within the highly privileged SYSTEM account context, effectively elevating their privileges from a standard user level to those of an administrator or system service. The exploitability hinges on the attacker's ability to interact with the WinSock ancillary functions through local processes that have sufficient permissions to invoke these specific API calls without triggering immediate access denied errors.
The operational impact of this vulnerability is severe, as it directly compromises the integrity and confidentiality of the host operating system by allowing unauthorized elevation of privileges. Once an attacker achieves SYSTEM-level access, they can install persistent backdoors, disable security monitoring tools such as Windows Defender or third-party endpoint detection solutions, exfiltrate sensitive data including credentials stored in memory or on disk, and pivot to other systems within the network infrastructure. This capability transforms a local account compromise into a full domain-wide threat if the compromised machine serves as a gateway for lateral movement. The presence of this flaw undermines the fundamental security model of Windows, which relies heavily on strict privilege separation between user-mode applications and kernel-mode components to contain potential breaches.
Industry standards classify this type of vulnerability under CWE-843, which refers to Access of Resource Using Incompatible Type, highlighting the failure in proper data typing during resource access. Furthermore, from a tactical perspective aligned with the MITRE ATT&CK framework, this exploit aligns with techniques such as T1068 Exploitation for Privilege Escalation and potentially T1055 Process Injection if the attacker utilizes memory manipulation to hide malicious activity after gaining higher privileges. The vulnerability represents a classic example of how low-level driver flaws can have high-impact consequences due to their proximity to core operating system functions.
Mitigation strategies primarily involve applying the latest security patches released by Microsoft, which address the underlying type checking logic within the WinSock ancillary function driver. Organizations should prioritize patching systems that expose this component to untrusted or semi-trusted local users, particularly servers and workstations with remote access capabilities. Additionally, implementing strict application whitelisting policies can prevent unauthorized processes from invoking vulnerable APIs even if the vulnerability remains present in the OS binaries. Security teams should also monitor for anomalous behavior indicative of privilege escalation attempts, such as sudden changes in process token privileges or unexpected interactions with kernel-mode drivers, using endpoint detection and response tools configured to flag these specific behavioral patterns associated with exploitation of type confusion flaws.