CVE-2026-56164
Critical 9.8 Exploited in the wild (KEV)
Confirmed active exploitation — CISA KEV catalog
- Name
- Microsoft SharePoint Server Missing Authentication for Critical Function Vulnerability
- Added to catalog
- Remediation due date (US federal)
- Required action
- 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.
Description
Missing authentication for critical function in Microsoft Office SharePoint allows an unauthorized attacker to elevate privileges over a network.
Metrics
- CVSS 3.1
-
9.8 (CRITICAL)
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 1% (percentile: 63) as of 1 November 2026
- CWE
- CWE-306
Affected products
microsoft: sharepoint server
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56164 Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026… US Government Resource