CVE-2026-56164 — Microsoft SharePoint Server Elevation of Privilege Vulnerability

Executive Summary

Missing authentication for critical function in Microsoft Office SharePoint allows an unauthorized attacker to elevate privileges over a network.

Overview

9.8

CVSS CRITICAL

Moderate

MS Severity

Exploited

MS Exploit Status

Exploitation Detected

MS Exploit Likelihood

Category Elevation of Privilege

Weakness CWE-306: Missing Authentication for Critical Function

Released Jul 14 2026

Last Updated Jul 14 2026

Publicly Disclosed No

CISA KEV Listed (added 2026-07-14)

Known Exploits None Known

EPSS Score 0.22439 — 0.97486 percentile

NVD CVSS 9.8 CRITICAL — differs from MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

ATTACK VECTOR

Network

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

None

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

None

INTEGRITY

Low

AVAILABILITY

None

EXPLOIT CODE MATURITY

Functional

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 4.9

EPSS Score

0.22439

probability of exploitation in the next 30 days

0.97486 percentile - updated 2026-08-14

View on FIRST.org

Affected Products

3 affected products

Product	KB Article	Severity	Impact	Restart Required
Microsoft SharePoint Enterprise Server 2016	`5002891 (Security Update)`	Moderate	Elevation of Privilege	Maybe
Microsoft SharePoint Server 2019	`5002883 (Security Update)`	Moderate	Elevation of Privilege	Maybe
Microsoft SharePoint Server Subscription Edition	`5002882 (Security Update)`	Moderate	Elevation of Privilege	Maybe

Patches

3 patches

Article	Type	Restart
`5002891`	Security Update	Maybe
`5002883`	Security Update	Maybe
`5002882`	Security Update	Maybe

Exploits & PoC

2 public PoCs

Unverified third-party code

Public proof-of-concept repositories aggregated from PoC-in-GitHub. They are not reviewed and may be incomplete, non-functional, or malicious — inspect the code before running anything.

Repository	Stars	Published	Description
sentinel-aidefense/CVE-2026-56164-EXP	14	2026-07-15	CVE-2026-56164 EOP Exploit
sam00/POC-CVE-2026-56164-exploit	2	2026-08-06	CVE-2026-56164 is a critical missing-authentication vulnerability affecting on-premises Microsoft SharePoint Server. It allows unauthenticated, remote attackers to elevate privileges over a network.

Detection Rules

No public Sigma or Nuclei detection rule has been mapped to this CVE yet. Coverage is concentrated on exploited / high-profile vulnerabilities; check SigmaHQ for updates.

Acknowledgments

Anonymous
Genwei Jiang with Google Cloud, FLARE OTF
Jayson Frost with Mandiant Incident Response

References

MSRC Advisory MITRE NVD