This vulnerability (CWE-79) in Microsoft SharePoint Server 2019 (version 16.0.0) arises from improper neutralization of input during web page generation, enabling cross-site scripting attacks. An attacker with authorized access can exploit this flaw to conduct spoofing attacks over a network. The CVSS 3.1 base score is 8.0, indicating high severity with network attack vector, low attack complexity, required privileges, and user interaction. Microsoft has published an official fix for this vulnerability.

Successful exploitation could allow an authorized attacker to execute arbitrary scripts in the context of the affected SharePoint web application, potentially leading to information disclosure, session hijacking, or other impacts associated with cross-site scripting. The vulnerability affects confidentiality, integrity, and availability (all rated high in CVSS).

An official fix is available from Microsoft. Users should apply the patch provided in the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-57105 to remediate this vulnerability.