CVE-2026-20963criticalunder attackCWE-502

CVE-2026-20963: critical vulnerability in Microsoft SharePoint Enterprise Server 2016

Microsoft SharePoint Remote Code Execution Vulnerability

Published · Updated

Follow this CVE+ Monitor Microsoft SharePoint Server+ Monitor Microsoft SharePoint Enterprise Server

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

63Vexday Risk Score

Prioritize patching. It under exploitation confirmed by CISA and has an official Brazilian government alert.

ssvc Actcvss 9.8epss 29%
from disclosure to weapon
Published on NVDJan 13
CISA KEV+64d
Official alert in Brazil

Brazil's federal government published an alert, recommendation or bulletin that cites this vulnerability.

Source: CTIR Gov (GSI) and CISC Gov.br, under the CC BY-ND 3.0 license.
Action required by CISAfederal deadline: 2026-03-21

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

In short

Microsoft SharePoint has a critical flaw that allows attackers to run malicious code on servers by sending specially crafted files. This happens because the software processes untrusted data without proper validation, putting all data on affected systems at risk.

Technical detail

CVE-2026-20963 exploits unsafe deserialization (CWE-502) in SharePoint's data processing, enabling remote code execution via network-based payload delivery. The vulnerability requires no authentication and allows an attacker to execute arbitrary code with SharePoint service privileges, affecting confidentiality, integrity, and availability of hosted content and systems.

Summary generated and translated by AI from the official description.

The full analysis of this CVE is available in Portuguese →

Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Affected products
Microsoft · Microsoft SharePoint Enterprise Server 2016Microsoft · Microsoft SharePoint Server 2019Microsoft · Microsoft SharePoint Server Subscription Edition
Related CVEs — Microsoft SharePoint Enterprise Server 2016

In the same product, most dangerous first.

CVE-2025-53770CRITICALMicrosoft SharePoint Server Remote Code Execution VulnerabilityEPSS 100.0%KEVCVE-2025-49704HIGHMicrosoft SharePoint Remote Code Execution VulnerabilityEPSS 100.0%KEVCVE-2023-29357CRITICALMicrosoft SharePoint Server Elevation of Privilege VulnerabilityEPSS 100.0%KEVCVE-2025-49706MEDIUMMicrosoft SharePoint Server Spoofing VulnerabilityEPSS 99.1%KEVCVE-2023-24955HIGHMicrosoft SharePoint Server Remote Code Execution VulnerabilityEPSS 85.0%KEVCVE-2026-45659HIGHMicrosoft SharePoint Remote Code Execution VulnerabilityEPSS 80.2%KEV