This vulnerability (CVE-2026-58644) in Microsoft SharePoint Enterprise Server 2016 is caused by improper handling of deserialization of untrusted data, classified under CWE-502. Exploitation enables remote code execution by an unauthenticated attacker over the network. The vulnerability affects version 16.0.0 of the product. Microsoft has released an official patch to address this issue, as documented in their security update guide.

Successful exploitation allows an attacker to execute arbitrary code remotely with no privileges required and no user interaction, potentially leading to full compromise of the affected SharePoint server. The vulnerability impacts confidentiality, integrity, and availability of the system.

An official fix is available from Microsoft. Users should apply the security update provided in the Microsoft advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58644 to remediate this vulnerability. No additional mitigations are indicated by the vendor.