This vulnerability occurs when the software fails to check the source markup of an application package, which leads to Remote Code Execution vulnerability in Microsoft SharePoint. Through page creation privileges permission in SharePoint, an unauthenticated user could exploit this bug by the means of leaking an arbitrary file, mainly the application’s web.config file, which could be utilized to perform RCE via .NET deserialization.
The attacker will be able to execute malicious code on the target server or client with high privileges.
In order to patch this vulnerability, we suggest you to test and apply the patched versions (https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-16952).