Security Resilience

CVE-2023-21539

Memory Safety in Microsoft Windows 10 20H2

Memory Safety
Published
10 January 2023
Modified
21 November 2024
CVSS Score v3.1 7.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.012 67th percentile
Risk Priority 64 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-2023-21539 is a high-severity Out-of-bounds Read (CWE-125) vulnerability in Microsoft Windows 10 20H2. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Data Obfuscation (T1001); ranked in the top 33% 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-2023-21539 is a remote code execution vulnerability affecting the Windows Authentication component. It carries a CVSS 3.1 base score of 7.5 and is associated with CWE-125. The flaw permits an attacker to execute arbitrary code on an affected system when specific conditions are met during authentication processing.

An authenticated user with low privileges can exploit the issue over a network connection, though successful exploitation requires high attack complexity and no user interaction. Successful attacks can result in full compromise of confidentiality, integrity, and availability on the target system.

Microsoft security advisories for CVE-2023-21539, available at the referenced MSRC update guide, detail the affected Windows versions and the corresponding security updates that address the vulnerability.

The EPSS score for this CVE rose from lower values to a peak of 0.0976 on 2025-01-22 before receding to the current 0.0305, indicating a period of increased exploitation interest after disclosure.

EU & UK References

Vulnerability Data

Windows Authentication Remote Code Execution Vulnerability

CWE(s)
CWE-125NVD-CWE-noinfo

Related Threats

MITRE ATT&CK Enterprise Techniques

T1001 Data Obfuscation Command And Control
Adversaries may obfuscate command and control traffic to make it more difficult to detect.
attack.mitre.org →
T1001.002 Steganography Command And Control
Adversaries may use steganographic techniques to hide command and control traffic to make detection efforts more difficult.
attack.mitre.org →
T1003.002 Security Account Manager Credential Access
Adversaries may attempt to extract credential material from the Security Account Manager (SAM) database either through in-memory techniques or through the Windows Registry where the SAM database is stored.
attack.mitre.org →
T1003.003 NTDS Credential Access
Adversaries may attempt to access or create a copy of the Active Directory domain database in order to steal credential information, as well as obtain other information about domain members such as devices, users, and access rights.
attack.mitre.org →
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 →
T1003.006 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 →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-21819Same product: Microsoft Windows 10 20H2
CVE-2023-35358Same product: Microsoft Windows 10 21H2
CVE-2023-24924Same product: Microsoft Windows 10 20H2
CVE-2023-24872Same product: Microsoft Windows 10 20H2
CVE-2023-35357Same product: Microsoft Windows 10 21H2
CVE-2024-26172Same product: Microsoft Windows 10 21H2
CVE-2023-36696Same product: Microsoft Windows 10 21H2
CVE-2023-21729Same product: Microsoft Windows 10 20H2
CVE-2023-21769Same product: Microsoft Windows 10 20H2
CVE-2024-29994Same product: Microsoft Windows 10 21H2

Affected Assets

microsoft
windows 10 20h2
all versions
microsoft
windows 10 21h2
all versions
microsoft
windows 10 22h2
all versions
microsoft
windows 11 21h2
all versions
microsoft
windows 11 22h2
all versions
microsoft
windows server 2022
all versions

Mitigating Controls

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.

ID.RA-01 partial match
blocks

Vulnerability scanning and recording can discover instances of out-of-bounds reads after code is deployed.

PR.PS-02 partial match
blocks

Routine patching replaces vulnerable code containing out-of-bounds read flaws.

PR.PS-06 partial match
blocks

Secure-development practices such as bounds checking and memory-safe languages directly prevent out-of-bounds reads.

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