<p>A security feature bypass vulnerability exists in SQL Server Reporting Services (SSRS) when the server improperly validates attachments uploaded to reports. An attacker who successfully exploited this vulnerability could upload file types that were disallowed by an administrator.</p> <p>To exploit the vulnerability, an authenticated attacker would need to send a specially crafted request to an affected SSRS server.</p> <p>The update addresses the vulnerability by modifying how SSRS validates attachment uploads.</p>
https://www.tenable.com/blog/microsoft-s-september-2020-patch-tuesday-addresses-129-cves
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1044