Microsoft SharePoint Server Missing Authentication for Critical Function Vulnerability
Microsoft — Microsoft SharePoint Enterprise Server 2016
Missing authentication for critical function in Microsoft Office SharePoint allows an unauthorized attacker to elevate privileges over a network.
5.3
26.6%
Vector breakdown
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
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
- Published
- Jul 14, 2026
- Modified
- Oct 28, 2026
- Added to KEV
- Jul 14, 2026
- Federal patch due
- Jul 17, 2026
CISA 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.
Weakness classification
Proof-of-concept & exploitation references
Weaponization
Public repositories whose name or description references CVE-2026-56164, found via a live GitHub search at request time. These are community-sourced signals, not a verified working exploit — cross-check each one before relying on it, and treat higher star counts and recent activity as (weak) corroboration, not proof.
No public GitHub repositories referencing CVE-2026-56164 were found at last check. Absence here is not proof no exploit exists — see the references below for vendor advisories and write-ups.
References
Frequently asked questions
What is CVE-2026-56164?
Missing authentication for critical function in Microsoft Office SharePoint allows an unauthorized attacker to elevate privileges over a network.
How severe is CVE-2026-56164?
CVE-2026-56164 has a CVSS base score of 5.3 out of 10 (CVSS 3.1).
Is CVE-2026-56164 actively exploited in the wild?
Yes. CVE-2026-56164 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added Jul 14, 2026, meaning CISA has confirmed evidence of active exploitation.
What is the EPSS score for CVE-2026-56164?
26.6% - meaning FIRST.org's EPSS model estimates a 26.6% probability this vulnerability will be exploited in the wild within 30 days (98% percentile among all scored CVEs).
What type of vulnerability is CVE-2026-56164?
CVE-2026-56164 is classified under CWE-306 (CWE-306: Missing Authentication for Critical Function).
Cross-checked against
Impactr finds and proves whether CVE-2026-56164 — or flaws like it — are actually reachable in your own web apps and APIs, with a reproducible exploit as evidence.