Security Resilience

CVE-2023-21716

Memory Safety in Microsoft Sharepoint Server 2019

High EPSSMemory Safety
Published
14 February 2023
Modified
19 August 2026
Patch / advisory
View advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.85 99.7th percentile
Risk Priority 97 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-2023-21716 is a critical-severity Integer Overflow or Wraparound (CWE-190) vulnerability in Microsoft Sharepoint Server. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique LSA Secrets (T1003.004); ranked in the top 0.3% 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-2023-21716 is a remote code execution vulnerability in Microsoft Word, carrying a CVSS 3.1 base score of 9.8 that reflects an integer overflow weakness (CWE-190) reachable over the network without authentication or user interaction. The flaw affects the Word application component and can result in complete loss of confidentiality, integrity, and availability on the target system.

An unauthenticated attacker positioned on the network can send a specially crafted document or request that triggers the flaw, allowing arbitrary code execution with the privileges of the Word process and full control over the affected host.

Microsoft security advisories published at the MSRC update guide for this CVE describe the available patches and urge customers to apply the fixes promptly to eliminate the exposure.

The associated EPSS score remains at a high level near 0.91 with no indicated rise from a low baseline.

EU & UK References

Vulnerability Data

Microsoft Word Remote Code Execution Vulnerability

CWE(s)
CWE-190NVD-CWE-noinfo

Related Threats

MITRE ATT&CK Enterprise Techniques

T1003.004 LSA Secrets Credential Access
Adversaries with SYSTEM access to a host may attempt to access Local Security Authority (LSA) secrets, which can contain a variety of different credential materials, such as credentials for service accounts.
attack.mitre.org →
T1003.005 Cached Domain Credentials Credential Access
Adversaries may attempt to access cached domain credentials used to allow authentication to occur in the event a domain controller is unavailable.
attack.mitre.org →
T1003.006 DCSync Credential Access
Adversaries may attempt to access credentials and other sensitive information by abusing a Windows Domain Controller's application programming interface (API)(Citation: Microsoft DRSR Dec 2017) (Citation: Microsoft GetNCCChanges) (Citati…
attack.mitre.org →
T1003.008 /etc/passwd and /etc/shadow Credential Access
Adversaries may attempt to dump the contents of <code>/etc/passwd</code> and <code>/etc/shadow</code> to enable offline password cracking.
attack.mitre.org →
T1006 Direct Volume Access Stealth
Adversaries may directly access a volume to bypass file access controls and file system monitoring.
attack.mitre.org →
T1008 Fallback Channels Command And Control
Adversaries may use fallback or alternate communication channels if the primary channel is compromised or inaccessible in order to maintain reliable command and control and to avoid data transfer thresholds.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-21379Same product: Microsoft Office
CVE-2023-36866Same product: Microsoft Office
CVE-2023-35372Same product: Microsoft Office
CVE-2023-28295Same product: Microsoft Office
CVE-2025-21338Same product: Microsoft Office
CVE-2026-97778Same product: Microsoft Office Online Server
CVE-2026-55026Same product: Microsoft Sharepoint Server
CVE-2026-44803Same product: Microsoft Word
CVE-2026-44812Same product: Microsoft Word
CVE-2026-69407Same vendor: Microsoft

Affected Assets

microsoft
office
2019
microsoft
office long term servicing channel
2021
microsoft
office online server
2016
microsoft
office web apps
2013
microsoft
sharepoint enterprise server
2013, 2016
microsoft
sharepoint foundation
2013
microsoft
sharepoint server
2019, all versions
microsoft
word
2013

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V5.2.6

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.PS-06 partial match
blocks

Secure SDLC practices directly require use of safe arithmetic, bounds checks, and testing that prevent integer overflows.

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.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.8.10 Information deletion partial match
removes

References