# CVE-2020-0639: Windows Common Log File System Driver Information Disclosure Vulnerability CVE-2020-0639 is fixed in 43 products on 1 platform, first by KB4534271, released January 14, 2020. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2020-0639 - Priority: Routine - CVSS: 5.5 (Important) - EPSS: 0.0140 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Vendor exploitability assessment: Exploitation Less Likely - Published: Jan 14, 2020 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2020-0639 ## Description

An information disclosure vulnerability exists in the Windows Common Log File System (CLFS) driver when it fails to properly handle objects in memory. An attacker who successfully exploited this vulnerability could potentially read data that was not intended to be disclosed. Note that this vulnerability would not allow an attacker to execute code or to elevate their user rights directly, but it could be used to obtain information that could be used to try to further compromise the affected system.

To exploit the vulnerability, an attacker would first have to log on to the system, and then run a specially crafted application to take control over the affected system.

The security update addresses the vulnerability by correcting how CLFS handles objects in memory.

## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Microsoft | Windows 10 Version 1607 for 32-bit Systems | 14393.3443 | [KB4534271](https://patchblox.com/security/data/fix/microsoft/kb4534271.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1607 for x64-based Systems | 14393.3443 | [KB4534271](https://patchblox.com/security/data/fix/microsoft/kb4534271.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1709 for 32-bit Systems | 16299.1625 | [KB4534276](https://patchblox.com/security/data/fix/microsoft/kb4534276.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1709 for ARM64-based Systems | 16299.1625 | [KB4534276](https://patchblox.com/security/data/fix/microsoft/kb4534276.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1709 for x64-based Systems | 16299.1625 | [KB4534276](https://patchblox.com/security/data/fix/microsoft/kb4534276.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1803 for 32-bit Systems | 17134.1246 | [KB4534293](https://patchblox.com/security/data/fix/microsoft/kb4534293.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1803 for ARM64-based Systems | 17134.1246 | [KB4534293](https://patchblox.com/security/data/fix/microsoft/kb4534293.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1803 for x64-based Systems | 17134.1246 | [KB4534293](https://patchblox.com/security/data/fix/microsoft/kb4534293.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1809 for 32-bit Systems | 17763.973 | [KB4534273](https://patchblox.com/security/data/fix/microsoft/kb4534273.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1809 for ARM64-based Systems | 17763.973 | [KB4534273](https://patchblox.com/security/data/fix/microsoft/kb4534273.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1809 for x64-based Systems | 17763.973 | [KB4534273](https://patchblox.com/security/data/fix/microsoft/kb4534273.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1903 for 32-bit Systems | | [KB4528760](https://patchblox.com/security/data/fix/microsoft/kb4528760.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1903 for ARM64-based Systems | | [KB4528760](https://patchblox.com/security/data/fix/microsoft/kb4528760.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1903 for x64-based Systems | | [KB4528760](https://patchblox.com/security/data/fix/microsoft/kb4528760.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1909 for 32-bit Systems | | [KB4528760](https://patchblox.com/security/data/fix/microsoft/kb4528760.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1909 for ARM64-based Systems | | [KB4528760](https://patchblox.com/security/data/fix/microsoft/kb4528760.md) | Jan 14, 2020 | | Microsoft | Windows 10 Version 1909 for x64-based Systems | | [KB4528760](https://patchblox.com/security/data/fix/microsoft/kb4528760.md) | Jan 14, 2020 | | Microsoft | Windows 10 for 32-bit Systems | 10240.18453 | [KB4534306](https://patchblox.com/security/data/fix/microsoft/kb4534306.md) | Jan 14, 2020 | | Microsoft | Windows 10 for x64-based Systems | 10240.18453 | [KB4534306](https://patchblox.com/security/data/fix/microsoft/kb4534306.md) | Jan 14, 2020 | | Microsoft | Windows 7 for 32-bit Systems Service Pack 1 | | [KB4534314](https://patchblox.com/security/data/fix/microsoft/kb4534314.md) | Jan 14, 2020 | | Microsoft | Windows 7 for 32-bit Systems Service Pack 1 | | [KB4534310](https://patchblox.com/security/data/fix/microsoft/kb4534310.md) | Jan 14, 2020 | | Microsoft | Windows 7 for x64-based Systems Service Pack 1 | | [KB4534314](https://patchblox.com/security/data/fix/microsoft/kb4534314.md) | Jan 14, 2020 | | Microsoft | Windows 7 for x64-based Systems Service Pack 1 | | [KB4534310](https://patchblox.com/security/data/fix/microsoft/kb4534310.md) | Jan 14, 2020 | | Microsoft | Windows 8.1 for 32-bit systems | | [KB4534309](https://patchblox.com/security/data/fix/microsoft/kb4534309.md) | Jan 14, 2020 | | Microsoft | Windows 8.1 for 32-bit systems | | [KB4534297](https://patchblox.com/security/data/fix/microsoft/kb4534297.md) | Jan 14, 2020 | | Microsoft | Windows 8.1 for x64-based systems | | [KB4534309](https://patchblox.com/security/data/fix/microsoft/kb4534309.md) | Jan 14, 2020 | | Microsoft | Windows 8.1 for x64-based systems | | [KB4534297](https://patchblox.com/security/data/fix/microsoft/kb4534297.md) | Jan 14, 2020 | | Microsoft | Windows RT 8.1 | | [KB4534297](https://patchblox.com/security/data/fix/microsoft/kb4534297.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 R2 for Itanium-Based Systems Service Pack 1 | | [KB4534314](https://patchblox.com/security/data/fix/microsoft/kb4534314.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 R2 for Itanium-Based Systems Service Pack 1 | | [KB4534310](https://patchblox.com/security/data/fix/microsoft/kb4534310.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 R2 for x64-based Systems Service Pack 1 | | [KB4534314](https://patchblox.com/security/data/fix/microsoft/kb4534314.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 R2 for x64-based Systems Service Pack 1 | | [KB4534310](https://patchblox.com/security/data/fix/microsoft/kb4534310.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) | | [KB4534314](https://patchblox.com/security/data/fix/microsoft/kb4534314.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) | | [KB4534310](https://patchblox.com/security/data/fix/microsoft/kb4534310.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 for 32-bit Systems Service Pack 2 | | [KB4534303](https://patchblox.com/security/data/fix/microsoft/kb4534303.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 for 32-bit Systems Service Pack 2 | | [KB4534312](https://patchblox.com/security/data/fix/microsoft/kb4534312.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation) | | [KB4534303](https://patchblox.com/security/data/fix/microsoft/kb4534303.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation) | | [KB4534312](https://patchblox.com/security/data/fix/microsoft/kb4534312.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 for Itanium-Based Systems Service Pack 2 | | [KB4534303](https://patchblox.com/security/data/fix/microsoft/kb4534303.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 for Itanium-Based Systems Service Pack 2 | | [KB4534312](https://patchblox.com/security/data/fix/microsoft/kb4534312.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 for x64-based Systems Service Pack 2 | | [KB4534303](https://patchblox.com/security/data/fix/microsoft/kb4534303.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 for x64-based Systems Service Pack 2 | | [KB4534312](https://patchblox.com/security/data/fix/microsoft/kb4534312.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) | | [KB4534303](https://patchblox.com/security/data/fix/microsoft/kb4534303.md) | Jan 14, 2020 | | Microsoft | Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) | | [KB4534312](https://patchblox.com/security/data/fix/microsoft/kb4534312.md) | Jan 14, 2020 | | Microsoft | Windows Server 2012 | | [KB4534288](https://patchblox.com/security/data/fix/microsoft/kb4534288.md) | Jan 14, 2020 | | Microsoft | Windows Server 2012 | | [KB4534283](https://patchblox.com/security/data/fix/microsoft/kb4534283.md) | Jan 14, 2020 | | Microsoft | Windows Server 2012 (Server Core installation) | | [KB4534288](https://patchblox.com/security/data/fix/microsoft/kb4534288.md) | Jan 14, 2020 | | Microsoft | Windows Server 2012 (Server Core installation) | | [KB4534283](https://patchblox.com/security/data/fix/microsoft/kb4534283.md) | Jan 14, 2020 | | Microsoft | Windows Server 2012 R2 | | [KB4534309](https://patchblox.com/security/data/fix/microsoft/kb4534309.md) | Jan 14, 2020 | | Microsoft | Windows Server 2012 R2 | | [KB4534297](https://patchblox.com/security/data/fix/microsoft/kb4534297.md) | Jan 14, 2020 | | Microsoft | Windows Server 2012 R2 (Server Core installation) | | [KB4534309](https://patchblox.com/security/data/fix/microsoft/kb4534309.md) | Jan 14, 2020 | | Microsoft | Windows Server 2012 R2 (Server Core installation) | | [KB4534297](https://patchblox.com/security/data/fix/microsoft/kb4534297.md) | Jan 14, 2020 | | Microsoft | Windows Server 2016 | 14393.3443 | [KB4534271](https://patchblox.com/security/data/fix/microsoft/kb4534271.md) | Jan 14, 2020 | | Microsoft | Windows Server 2016 (Server Core installation) | 14393.3443 | [KB4534271](https://patchblox.com/security/data/fix/microsoft/kb4534271.md) | Jan 14, 2020 | | Microsoft | Windows Server 2019 | 17763.973 | [KB4534273](https://patchblox.com/security/data/fix/microsoft/kb4534273.md) | Jan 14, 2020 | | Microsoft | Windows Server 2019 (Server Core installation) | 17763.973 | [KB4534273](https://patchblox.com/security/data/fix/microsoft/kb4534273.md) | Jan 14, 2020 | | Microsoft | Windows Server, version 1803 (Server Core Installation) | 17134.1246 | [KB4534293](https://patchblox.com/security/data/fix/microsoft/kb4534293.md) | Jan 14, 2020 | | Microsoft | Windows Server, version 1903 (Server Core installation) | | [KB4528760](https://patchblox.com/security/data/fix/microsoft/kb4528760.md) | Jan 14, 2020 | | Microsoft | Windows Server, version 1909 (Server Core installation) | | [KB4528760](https://patchblox.com/security/data/fix/microsoft/kb4528760.md) | Jan 14, 2020 | --- Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.