CVE-2026-56164mediumunder attackCWE-306

CVE-2026-56164: medium-severity vulnerability in Microsoft SharePoint Enterprise Server 2016

Microsoft SharePoint Server Elevation of Privilege Vulnerability

Published · Updated

63Vexday Risk Score

Prioritize patching. It under exploitation confirmed by CISA and has a public proof of concept.

ssvc Actcvss 5.3epss 1.0%
from disclosure to weapon1 days
Published on NVDJul 14
1st PoC+1d
CISA KEVJul 14
victimsAug 4
exploitation probability
1.0%top 38% of all CVEs
observed exploitation
yesCISA + VulnCheck
2 public exploit(s)
Appeared in 1 incident(s) we investigated
FOITT / BIT (Escritório Federal de Tecnologia da Informação e Telecomunicações da Suíça)
Action required by CISAfederal deadline: 2026-07-17

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

In short

Microsoft SharePoint Server is missing authentication checks on a critical function, allowing an attacker on the network to gain higher privileges without proper credentials.

Technical detail

CWE-306 (Missing Authentication) in SharePoint Server permits an unauthenticated or low-privileged attacker to invoke a critical function over the network, resulting in elevation of privilege. The vulnerability stems from insufficient access controls on a sensitive operation, requiring only network connectivity as a prerequisite.

Summary generated and translated by AI from the official description.

The full analysis of this CVE is available in Portuguese →

Missing authentication for critical function in Microsoft Office SharePoint allows an unauthorized attacker to elevate privileges over a network.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:F/RL:O/RC:C
Affected products
Microsoft · Microsoft SharePoint Enterprise Server 2016Microsoft · Microsoft SharePoint Server 2019Microsoft · Microsoft SharePoint Server Subscription Edition
public PoCs found — 2
githubgithub.com/sentinel-aidefense/CVE-2026-56164-EXP★ 12githubgithub.com/sam00/POC-CVE-2026-56164-exploit★ 2
⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
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-2026-55040CRITICALMicrosoft SharePoint Server Security Feature Bypass VulnerabilityEPSS 69.5%KEV
References
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56164https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-56164