CVE-2026-34335
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Use After Free in Windows Ancillary Function Driver for WinSock

Publication date: 2026-06-09

Last updated on: 2026-06-09

Assigner: Microsoft Corporation

Description
Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
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Meta Information
Published
2026-06-09
Last Modified
2026-06-09
Generated
2026-06-10
AI Q&A
2026-06-09
EPSS Evaluated
N/A
NVD
CVE-2026-34335
EUVD
EUVD-2026-35658
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
microsoft windows_ancillary_function_driver_for_winsock *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-416 The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
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Mitigation Strategies

To mitigate this vulnerability, apply the security updates provided by Microsoft for the Windows Ancillary Function Driver for WinSock as soon as they become available.

Since the vulnerability allows local privilege escalation, ensure that only authorized users have local access to affected systems and monitor for unusual privilege escalation attempts.

Impact Analysis

An attacker who exploits this vulnerability can gain higher privileges on the local system than they are normally authorized to have. This elevation of privilege can lead to unauthorized access to sensitive information, modification of system settings, or installation of malicious software.

Executive Summary

This vulnerability is a use after free issue in the Windows Ancillary Function Driver for WinSock. It allows an authorized attacker to elevate their privileges locally on the affected system.

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