CVE-2021-40483: 
vulnerability analysis and mitigation

Microsoft SharePoint Server Spoofing Vulnerability (CVE-2021-40483) was disclosed on October 12, 2021. This vulnerability affects Microsoft SharePoint Server 2019 installations. The vulnerability is unique and distinct from CVE-2021-40484, which was disclosed during the same period (NVD CVE).

The vulnerability has received varying severity assessments. According to the NVD, it has a CVSS v3.1 Base Score of 3.5 (LOW) with a vector string of CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N. However, Microsoft Corporation's assessment indicates a higher severity with a CVSS v3.1 Base Score of 7.6 (HIGH) and a vector string of CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N. The vulnerability is classified under CWE-NVD-noinfo due to insufficient information (NVD CVE).

Based on the CVSS scores and vector strings, the vulnerability could potentially lead to information disclosure and integrity impacts. The higher severity rating from Microsoft suggests potential for significant confidentiality breach (C:H) and limited integrity impact (I:L) in the context of their assessment (NVD CVE).

Microsoft has released a security update to address this vulnerability. The fix is included in the SharePoint Server 2019 security update package (KB5002028) released on October 12, 2021. Organizations are advised to apply this security update to protect against potential exploitation (Microsoft Support).