Microsoft Windows up to Server 2019 Projected Filesystem input validation

Summaryinfo

A vulnerability was found in Microsoft Windows up to Server 2019. It has been classified as problematic. Affected by this vulnerability is an unknown functionality of the component Projected Filesystem. This manipulation causes input validation. This vulnerability appears as CVE-2020-16879. The attack may be initiated remotely. There is no available exploit. To fix this issue, it is recommended to deploy a patch.

Detailsinfo

A vulnerability was found in Microsoft Windows up to Server 2019 (Operating System). It has been declared as problematic. Affected by this vulnerability is an unknown code block of the component Projected Filesystem. The manipulation with an unknown input leads to a input validation vulnerability. The CWE definition for the vulnerability is CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. As an impact it is known to affect confidentiality. The summary by CVE is:

<p>An information disclosure vulnerability exists when a Windows Projected Filesystem improperly handles file redirections. An attacker who successfully exploited this vulnerability could obtain information to further compromise the user's system</p> <p>To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerability.</p> <p>The security update addresses the vulnerability by correcting how Windows Projected Filesystem handle file redirections.</p>

The weakness was presented 09/08/2020 as confirmed security update guide (Website). It is possible to read the advisory at portal.msrc.microsoft.com. The public release was coordinated in cooperation with Microsoft. This vulnerability is known as CVE-2020-16879. The attack can be launched remotely. The requirement for exploitation is a single authentication. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 02/24/2026). The advisory points out:

An information disclosure vulnerability exists when a Windows Projected Filesystem improperly handles file redirections. An attacker who successfully exploited this vulnerability could obtain information to further compromise the user's system

Applying a patch is able to eliminate this problem. A possible mitigation has been published immediately after the disclosure of the vulnerability.

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Productinfo

Type

• Operating System

Vendor

• Microsoft

Name

• Windows

Version

• 10 1809
• 10 1903
• 10 1909
• 10 2004
• Server 1903
• Server 1909
• Server 2004
• Server 2019

License

• commercial

Website

• Vendor: https://www.microsoft.com/
• Product: https://www.microsoft.com/en-us/windows

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