Microsoft Windows up to Server 2019 dnsrslvr.dll memory corruption

Summaryinfo

A vulnerability described as critical has been identified in Microsoft Windows. This affects an unknown function in the library dnsrslvr.dll. The manipulation results in memory corruption. This vulnerability is reported as CVE-2020-0839. The attack requires a local approach. No exploit exists. Applying a patch is advised to resolve this issue.

Detailsinfo

A vulnerability was found in Microsoft Windows (Operating System). It has been classified as critical. Affected is an unknown code block in the library dnsrslvr.dll. The manipulation with an unknown input leads to a memory corruption vulnerability. CWE is classifying the issue as CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

<p>An elevation of privilege vulnerability exists in the way that the dnsrslvr.dll handles objects in memory. An attacker who successfully exploited the vulnerability could execute code with elevated permissions.</p> <p>To exploit the vulnerability, a locally authenticated attacker could run a specially crafted application.</p> <p>The security update addresses the vulnerability by ensuring the dnsrslvr.dll properly handles objects in memory.</p>

The weakness was disclosed 09/08/2020 as confirmed security update guide (Website). The advisory is shared for download at portal.msrc.microsoft.com. The public release has been coordinated in cooperation with the vendor. This vulnerability is traded as CVE-2020-0839. The attack needs to be approached locally. The requirement for exploitation is a authentication. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 02/24/2026). The advisory points out:

An elevation of privilege vulnerability exists in the way that the dnsrslvr.dll handles objects in memory. An attacker who successfully exploited the vulnerability could execute code with elevated permissions.

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

The entries VDB-160876, VDB-160875, VDB-160874 and VDB-160873 are pretty similar. VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Operating System

Vendor

• Microsoft

Name

• Windows

Version

• 10
• 10 1607
• 10 1709
• 10 1803
• 10 1809
• 10 1903
• 10 1909
• 10 2004
• Server 1903
• Server 1909
• Server 2004
• Server 2016
• Server 2019

License

• commercial

Website

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

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