CVE-2026-85355

Analyzed Analyzed - Analysis Complete

Windows CLFS Driver Privilege Escalation Vulnerability

Publication date: 2026-10-13

Last updated on: 2026-10-28

Assigner: Microsoft Corporation

Description

Inclusion of functionality from untrusted control sphere in Windows Common Log File System Driver allows an authorized attacker to elevate privileges locally.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-10-13

Last Modified

2026-10-28

Generated

2026-11-08

AI Q&A

2026-10-14

EPSS Evaluated

2026-11-07

NVD

CVE-2026-85355

EUVD

EUVD-2026-99481

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	windows_server_2012	r2
microsoft	windows_server_2012	*
microsoft	windows_server_2022	to 10.0.20348.5761 (exc)
microsoft	windows_10_1607	to 10.0.14393.9612 (exc)
microsoft	windows_10_1607	to 10.0.14393.9612 (exc)
microsoft	windows_10_1809	to 10.0.17763.9376 (exc)
microsoft	windows_10_1809	to 10.0.17763.9376 (exc)
microsoft	windows_10_21h2	to 10.0.19044.7807 (exc)
microsoft	windows_10_21h2	to 10.0.19044.7807 (exc)
microsoft	windows_10_21h2	to 10.0.19044.7807 (exc)
microsoft	windows_11_23h2	to 10.0.22631.7652 (exc)
microsoft	windows_11_23h2	to 10.0.22631.7652 (exc)
microsoft	windows_11_24h2	to 10.0.26100.9711 (exc)
microsoft	windows_11_24h2	to 10.0.26100.9711 (exc)
microsoft	windows_11_25h2	to 10.0.26200.9711 (exc)
microsoft	windows_11_25h2	to 10.0.26200.9711 (exc)
microsoft	windows_11_26h1	to 10.0.28000.3231 (exc)
microsoft	windows_11_26h1	to 10.0.28000.3231 (exc)
microsoft	windows_11_26h2	to 10.0.26300.9711 (exc)
microsoft	windows_11_26h2	to 10.0.26300.9711 (exc)
microsoft	windows_server_2016	to 10.0.14393.9612 (exc)
microsoft	windows_server_2019	to 10.0.17763.9376 (exc)
microsoft	windows_server_2025	to 10.0.26100.33650 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7807 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7807 (exc)
microsoft	windows_10_22h2	to 10.0.19045.7807 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-829	The product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere.

Attack-Flow Graph

Executive Summary

This vulnerability involves the Windows Common Log File System Driver improperly including functionality from an untrusted source. An authorized attacker can exploit this to elevate their privileges locally on affected systems.

Detection Guidance

This vulnerability involves local privilege escalation in the Windows Common Log File System Driver. Detection typically requires checking for unusual privilege changes or unauthorized modifications to system logs. Use Windows Event Viewer to review logs for unexpected privilege escalation events in the Security log. Check for events related to the Common Log File System Driver (clfs.sys) or privilege changes by users.

Impact Analysis

An attacker could gain higher-level access to your system, allowing them to perform unauthorized actions such as installing malicious software, accessing sensitive data, or taking control of your device.

Compliance Impact

This vulnerability allows local privilege escalation in Windows systems via the Common Log File System Driver. While not directly impacting GDPR or HIPAA compliance, such privilege escalation could enable unauthorized access to sensitive data, potentially violating confidentiality requirements under these regulations if exploited.

Mitigation Strategies

Apply the latest security updates from Microsoft to patch the Windows Common Log File System Driver vulnerability. Monitor Microsoft's update guide for patches and install them as soon as available.

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