CVE-2026-34346 in Windows
Summary
by MITRE • 07/14/2026
Cleartext transmission of sensitive information in Windows Ancillary Function Driver for WinSock allows an authorized attacker to disclose information locally.
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Analysis
by VulDB Data Team • 07/14/2026
The vulnerability described involves cleartext transmission of sensitive information within the Windows Ancillary Function Driver for WinSock component, representing a significant security weakness that enables local information disclosure attacks. This flaw exists in the core networking infrastructure of Windows operating systems, specifically affecting how socket operations are handled through the ancillary function driver interface. The issue stems from improper encryption or encoding of sensitive data during transmission between network components, creating an attack surface that authorized malicious users can exploit to gain unauthorized access to confidential information.
The technical implementation of this vulnerability resides in the WinSock ancillary function driver's handling of network communication protocols and data processing routines. When applications interact with network services through Windows socket APIs, the ancillary function driver processes these requests and manages the underlying network operations. The flaw occurs during data transmission phases where sensitive information flows through the system without adequate protection mechanisms, allowing attackers to intercept and read plaintext data that should remain encrypted or protected. This represents a violation of fundamental security principles governing data confidentiality in network communications.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable more sophisticated attack vectors including credential theft, session hijacking, and privilege escalation within local network environments. Attackers with authorized access to the system can leverage this weakness to capture sensitive data flowing through network sockets, potentially compromising user authentication credentials, application data, or system configuration details. The local nature of the vulnerability means that attackers do not require external network access or complex exploitation techniques, significantly reducing the barrier to successful attacks while maintaining persistent access to valuable information assets.
Mitigation strategies for this vulnerability encompass multiple layers of security controls including immediate patch deployment from Microsoft security updates, implementation of network traffic encryption protocols such as TLS/SSL for all socket communications, and comprehensive monitoring of network activities for suspicious data transmission patterns. System administrators should implement network segmentation policies to limit local access privileges and establish robust logging mechanisms to detect unauthorized data access attempts. Additionally, organizations must conduct regular vulnerability assessments targeting Windows networking components and ensure proper configuration management of socket-based applications to prevent exploitation of this cleartext transmission weakness.
This vulnerability aligns with CWE-312 (Cleartext Storage of Sensitive Information) and CWE-319 (Cleartext Transmission of Sensitive Information) classifications, which specifically address the improper handling of sensitive data in storage and transmission contexts. From an ATT&CK framework perspective, this weakness maps to T1041 (Exfiltration Over C2 Channel) and T1567 (Exfiltration Over Web Service) techniques, as attackers can leverage local network access to extract sensitive information through established socket communications. The vulnerability demonstrates how fundamental security controls in operating system components can be compromised, highlighting the critical need for proper encryption implementation throughout all network communication layers.
Organizations should prioritize immediate remediation through Microsoft security patches while implementing additional defensive measures such as network traffic analysis tools, application whitelisting policies, and comprehensive security awareness training for system administrators. The vulnerability serves as a reminder of the importance of maintaining up-to-date security controls and the potential consequences of insufficient encryption practices in critical system components. Regular security audits focusing on ancillary function drivers and socket-based communications should be conducted to identify similar weaknesses that could compromise system integrity and data confidentiality across enterprise environments.