CVE-2026-34335

Analyzed Analyzed - Analysis Complete

Use After Free in Windows Ancillary Function Driver for WinSock

Publication date: 2026-06-09

Last updated on: 2026-06-10

Assigner: Microsoft Corporation

Description

Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-06-09

Last Modified

2026-06-10

Generated

2026-06-30

AI Q&A

2026-06-09

EPSS Evaluated

2026-06-28

NVD

CVE-2026-34335

EUVD

EUVD-2026-35658

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	windows_server_2012	r2
microsoft	windows_server_2012	*
microsoft	windows_10_1607	to 10.0.14393.9234 (exc)
microsoft	windows_10_1607	to 10.0.14393.9234 (exc)
microsoft	windows_10_1809	to 10.0.17763.8880 (exc)
microsoft	windows_10_1809	to 10.0.17763.8880 (exc)
microsoft	windows_10_21h2	to 10.0.19044.7417 (exc)
microsoft	windows_10_21h2	to 10.0.19044.7417 (exc)
microsoft	windows_10_21h2	to 10.0.19044.7417 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7417 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7417 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7417 (exc)
microsoft	windows_11_23h2	to 10.0.22631.7219 (exc)
microsoft	windows_11_23h2	to 10.0.22631.7219 (exc)
microsoft	windows_11_24h2	to 10.0.26100.8655 (exc)
microsoft	windows_11_24h2	to 10.0.26100.8655 (exc)
microsoft	windows_11_25h2	to 10.0.26200.8655 (exc)
microsoft	windows_11_25h2	to 10.0.26200.8655 (exc)
microsoft	windows_11_26h1	to 10.0.28000.2269 (exc)
microsoft	windows_11_26h1	to 10.0.28000.2269 (exc)
microsoft	windows_server_2016	to 10.0.14393.9234 (exc)
microsoft	windows_server_2019	to 10.0.17763.8880 (exc)
microsoft	windows_server_2022	to 10.0.20348.5256 (exc)
microsoft	windows_server_2025	to 10.0.26100.32995 (exc)

Helpful Resources

Exploitability

CWE

KEV

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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Attack-Flow Graph

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.

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.

Compliance Impact

The vulnerability allows an authorized attacker to elevate privileges locally through a use after free in the Windows Ancillary Function Driver for WinSock.

Such elevation of privilege vulnerabilities can potentially lead to unauthorized access or modification of sensitive data, which may impact compliance with standards and regulations like GDPR and HIPAA that require protection of personal and health information.

However, the provided information does not explicitly describe the direct impact on compliance with these standards.

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