Cyber Resilience

CVE-2026-56164

Access Control in Microsoft Sharepoint Server ≤ 16.0.19725.20434

CISA KEVActive ExploitationEUVD ExploitedAccess Control
Published
14 July 2026
Modified
14 July 2026
KEV Added
14 July 2026
Patch / advisory
View advisory
CVSS Score v3.1 5.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
EPSS Score 0.20 97th percentile
Risk Priority 64 floored blend · peak EPSS

Summary

CVE-2026-56164 is a medium-severity Missing Authentication for Critical Function (CWE-306) vulnerability in Microsoft Sharepoint Server. Its CVSS base score is 5.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 3% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and IA-2 (Identification and Authentication (Organizational Users)) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A07:2025 Authentication Failures

EU & UK References

Vulnerability Data

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

CWE(s)
CWE-306
KEV Date Added
14 July 2026

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Why these techniques?

Missing authentication (CWE-306) in public-facing SharePoint directly enables remote exploitation for privilege escalation (T1190, T1068).

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

Likely ATT&CK TechniquesAI

Techniques this vulnerability likely enables, inferred from its description, weakness type, and attributed-actor tradecraft. Confidence is per-technique.

T1190 Exploit Public-Facing Application Initial Accessconfidence: HIGH
Missing auth on critical SharePoint function directly enables exploitation of this public-facing app for unauthorized access.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalationconfidence: HIGH
The vulnerability explicitly allows an unauthenticated attacker to elevate privileges over the network.
attack.mitre.org →
inferred from description + CWE · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2023-21743Same product: Microsoft Sharepoint Server
CVE-2023-29357Same product: Microsoft Sharepoint Serverboth on KEV
CVE-2023-33159Same product: Microsoft Sharepoint Server
CVE-2023-36764Same product: Microsoft Sharepoint Server
CVE-2023-36892Same product: Microsoft Sharepoint Server
CVE-2026-26125Same vendor: Microsoft
CVE-2023-33157Same product: Microsoft Sharepoint Server
CVE-2023-24955Same product: Microsoft Sharepoint Serverboth on KEV
CVE-2023-36891Same product: Microsoft Sharepoint Server
CVE-2023-36890Same product: Microsoft Sharepoint Server

Affected Assets

microsoft
sharepoint server
2016, 2019 · ≤ 16.0.19725.20434

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • AC-3 Access Enforcement
  • IA-2 Identification and Authentication (Organizational Users)
  • AC-17 Remote Access
Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 6 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V6.2.3
  • V6.4.4
  • V10.4.16
  • V12.1.3

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match
prevent

Directly enforces authentication and authorization checks on critical SharePoint functions, blocking the unauthorized privilege escalation path described in CWE-306.

IA-2 Identification and Authentication (Organizational Users) good match
prevent

Requires unique identification and authentication of organizational users before allowing access to SharePoint resources, directly mitigating missing authentication for critical functions.

AC-17 Remote Access partial match
prevent

Mandates authentication and access controls for all remote/network connections to SharePoint, limiting the network-based attack vector in the CVE.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-03 full match
prevents

Directly requires authentication of users/services/hardware, which eliminates missing authentication for critical functions.

PR.AA-01 partial match
prevents

Managing identities and credentials is a prerequisite for authentication but does not itself enforce it on critical functions.

PR.AA-05 partial match
prevents

Defining and enforcing authorizations assumes prior authentication and therefore only partially mitigates the absence of authentication.

PR.IR-01 partial match
prevents

Protecting networks from unauthorized access can be undermined by missing authentication but does not address the root authentication gap.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.5 Secure authentication full match
prevents

The control explicitly calls for authentication before any critical function is reached, eliminating the possibility of bypassing authentication for high-value operations.

A.5.8 Information security in project management partial match
prevents

Mandating authentication requirements for critical functions at the requirements-gathering stage ensures that essential operations are not left unprotected by missing login or verification mechanisms.

A.8.21 Security of network services partial match
mitigates

Mandating authentication for network services and critical functions stops attackers from invoking sensitive operations without credentials, closing gaps where authentication is absent for important capabilities.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Security engineering principles insist on authentication and authorization for every critical function, eliminating entry points that lack any access control mechanism.

A.6.7 Remote working none match
none

Requiring strong authentication and access-privilege enablement for remote connections ensures that critical functions cannot be invoked without proper verification, closing a gap that would otherwise allow unauthenticated use.

A.7.2 Physical entry none match
none

Mandatory use of access cards, biometrics, or two-factor authentication ensures that critical physical areas cannot be entered without proper authentication.

References