Security Resilience

CVE-2023-21743

Access Control in Microsoft Sharepoint Server 2016 … 2019

Published
10 January 2023
Modified
21 November 2024
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 0.011 66th percentile
Risk Priority 54 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-21743 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 System Service Discovery (T1007); ranked in the top 34% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2023-21743 is a security feature bypass vulnerability in Microsoft SharePoint Server, assigned CWE-306 for missing authentication on a critical function. It carries a CVSS 3.1 base score of 5.3 reflecting network attack vector, low complexity, no required privileges or user interaction, and limited integrity impact without affecting confidentiality or availability.

An unauthenticated remote attacker can exploit the flaw to bypass intended security controls and perform limited unauthorized modifications to SharePoint content or configuration. The attack requires no credentials and can be launched over the network with minimal effort.

Microsoft has published remediation guidance in its Security Response Center advisory at the listed MSRC URL, directing administrators to apply the corresponding security updates for affected SharePoint Server versions. The associated EPSS score has remained flat at 0.1160 with no material increase after disclosure.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

Microsoft SharePoint Server Security Feature Bypass Vulnerability

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1007 System Service Discovery Discovery
Adversaries may try to gather information about registered local system services.
T1010 Application Window Discovery Discovery
Adversaries may attempt to get a listing of open application windows.
T1016 System Network Configuration Discovery Discovery
Adversaries may look for details about the network configuration and settings, such as IP and/or MAC addresses, of systems they access or through information discovery of remote systems.
T1027.004 Compile After Delivery Stealth
Adversaries may attempt to make payloads difficult to discover and analyze by delivering files to victims as uncompiled code.
T1027.006 HTML Smuggling Stealth
Adversaries may smuggle data and files past content filters by hiding malicious payloads inside of seemingly benign HTML files.
T1027.007 Dynamic API Resolution Stealth
Adversaries may obfuscate then dynamically resolve API functions called by their malware in order to conceal malicious functionalities and impair defensive analysis.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-56164Same product: Microsoft Sharepoint Server
CVE-2026-64921Same product: Microsoft Sharepoint Server
CVE-2023-29357Same product: Microsoft Sharepoint Server
CVE-2023-36764Same product: Microsoft Sharepoint Server
CVE-2023-36892Same product: Microsoft Sharepoint Server
CVE-2023-36891Same product: Microsoft Sharepoint Server
CVE-2023-33159Same product: Microsoft Sharepoint Server
CVE-2023-33130Same product: Microsoft Sharepoint Server
CVE-2023-33132Same product: Microsoft Sharepoint Server
CVE-2023-33157Same product: Microsoft Sharepoint Server

Affected Assets

microsoft
sharepoint server
2016, 2019, all versions

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

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

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-306

Requires established identification and authentication to unlock, mitigating missing authentication for continued system access.

addresses: CWE-306

Requiring identification and rationale for actions allowed without authentication ensures critical functions are not left unprotected by forcing review of authentication requirements.

addresses: CWE-306

Authorizing mobile device connections to organizational systems ensures authentication is performed for this critical access function.

addresses: CWE-306

Guarantees critical functions are protected by mandatory invocation of the access control mechanism.

addresses: CWE-306

Auditing sessions makes it possible to detect access to critical functions without required authentication.

addresses: CWE-306

The assessment process confirms authentication is present and effective for critical functions, preventing exploitation from missing authentication.

addresses: CWE-306

Certification assesses that critical functions have required authentication controls in place.

addresses: CWE-306

Disabling non-essential functions and services eliminates the need to secure them, reducing exposure from missing authentication on unnecessary components.

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-01 partial match
blocks

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

PR.AA-03 partial match
blocks

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

PR.AA-05 partial match
blocks

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

PR.IR-01 partial match
blocks

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.

removes
removes
removes
blocks

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.

removes

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).

Oracle Linux 8 (2 rules)
  • V-248585 OL 8 must require reauthentication when using the "sudo" command. blocks CWE-306
  • V-248827 OL 8 must not have the rsh-server package installed. blocks CWE-306
RHEL 7 (2 rules)
  • V-204442 The Red Hat Enterprise Linux operating system must not have the rsh-server package installed. blocks CWE-306
  • V-237635 The Red Hat Enterprise Linux operating system must require re-authentication when using the "sudo" command. blocks CWE-306
RHEL 8 (2 rules)
  • V-230492 RHEL 8 must not have the rsh-server package installed. blocks CWE-306
  • V-237643 RHEL 8 must require re-authentication when using the "sudo" command. blocks CWE-306

References