This vulnerability (CWE-79) in Microsoft SharePoint Enterprise Server 2016 (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 perform spoofing over a network. The vulnerability has a CVSS 3.1 base score of 7.3 (high severity) with network attack vector, low attack complexity, required privileges, and user interaction. Microsoft has released an official fix for this issue.

Successful exploitation can lead to high impact on confidentiality and integrity, allowing an attacker to spoof content or perform actions on behalf of users. Availability impact is not affected. The vulnerability requires an authorized user and user interaction to exploit.

An official fix is available from Microsoft. Users of Microsoft SharePoint Enterprise Server 2016 version 16.0.0 should apply the vendor-provided patch as detailed in the Microsoft security advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55021 to remediate this vulnerability.