Microsoft Windows up to Server 2019 AppXSVC access control

Summaryinfo

A vulnerability, which was classified as critical, has been found in Microsoft Windows up to Server 2019. This affects an unknown part of the component AppXSVC. Performing a manipulation results in access control. This vulnerability is reported as CVE-2019-1064. The attack is possible to be carried out remotely. Moreover, an exploit is present. 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 classified as critical. This affects an unknown functionality of the component AppXSVC. The manipulation with an unknown input leads to a access control vulnerability. CWE is classifying the issue as CWE-264. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

An elevation of privilege vulnerability exists when Windows AppX Deployment Service (AppXSVC) improperly handles hard links. An attacker who successfully exploited this vulnerability could run processes in an elevated context. An attacker could then install programs; view, change or delete data. 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 and take control of an affected system. The security update addresses the vulnerability by correcting how Windows AppX Deployment Service handles hard links.

The weakness was disclosed 06/11/2019 as confirmed security update guide (Website). It is possible to read the advisory at portal.msrc.microsoft.com. The public release has been coordinated in cooperation with Microsoft. This vulnerability is uniquely identified as CVE-2019-1064 since 11/26/2018. It is possible to initiate the attack remotely. The successful exploitation needs a authentication. Technical details are unknown but an exploit is available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 10/29/2025). The attack technique deployed by this issue is T1068 according to MITRE ATT&CK. The advisory points out:

An elevation of privilege vulnerability exists when Windows AppX Deployment Service (AppXSVC) improperly handles hard links. An attacker who successfully exploited this vulnerability could run processes in an elevated context. An attacker could then install programs; view, change or delete data.

It is declared as attacked. The commercial vulnerability scanner Qualys is able to test this issue with plugin 91544 (Microsoft Windows Security Update for June 2019). The CISA Known Exploited Vulnerabilities Catalog lists this issue since 03/15/2022 with a due date of 04/05/2022:

Apply updates per vendor instructions.

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-136274, VDB-136286, VDB-136287 and VDB-136296 are pretty similar. Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Microsoft

Name

• Windows

Version

• 10 1607
• 10 1703
• 10 1709
• 10 1803
• 10 1809
• 10 1903
• Server 1803
• Server 1903
• Server 2016
• Server 2019

License

• commercial

Website

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

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