Cyber Resilience

CVE-2021-1732

Memory Safety in Microsoft Windows 10 1803

CISA KEVActive ExploitationEUVD ExploitedPublic PoCRansomware-linkedMemory Safety
Published
25 February 2021
Modified
12 August 2026
KEV Added
03 November 2021
Patch / advisory
CVSS Score v3.1 7.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.78 99.5th percentile
Risk Priority 83 floored blend · peak EPSS

Summary

CVE-2021-1732 is a high-severity Out-of-bounds Write (CWE-787) vulnerability in Microsoft Windows 10 1803. Its CVSS base score is 7.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 0.5% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

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-2021-1732 is an elevation of privilege vulnerability in the Win32k component of Windows, assigned a CVSS 3.1 base score of 7.8 and categorized under CWE-787 for out-of-bounds write issues. The flaw stems from an offset confusion condition in ConsoleControl handling within the kernel-mode driver.

Local attackers with low privileges can exploit the vulnerability without user interaction to obtain full control over the affected system, resulting in high impact to confidentiality, integrity, and availability. Public proof-of-concept code demonstrating the offset confusion technique for privilege escalation has been published on PacketStorm.

Microsoft's security advisory at portal.msrc.microsoft.com provides official guidance on the issue, while multiple exploit implementations confirm the flaw's practical exploitability on unpatched systems.

EU & UK References

Vulnerability Data

Windows Win32k Elevation of Privilege Vulnerability

CWE(s)
KEV Date Added
03 November 2021

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
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.
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
T1211 Exploitation for Stealth Stealth
Adversaries may exploit vulnerabilities to evade detection by hiding activity, suppressing logging, or operating within trusted or unmonitored components.
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2021-28310Same product: Microsoft Windows 10 1803both on KEV
CVE-2022-21882Same product: Microsoft Windows 10 1809both on KEV
CVE-2020-0986Same product: Microsoft Windows 10 1803both on KEV
CVE-2021-33742Same product: Microsoft Windows 10 1809both on KEV
CVE-2021-34448Same product: Microsoft Windows 10 1809both on KEV
CVE-2020-1020Same product: Microsoft Windows 10 1803both on KEV
CVE-2020-1380Same product: Microsoft Windows 10 1803both on KEV
CVE-2022-24521Same product: Microsoft Windows 10 1809both on KEV
CVE-2020-1027Same product: Microsoft Windows 10 1803both on KEV
CVE-2020-0938Same product: Microsoft Windows 10 1803both on KEV

Affected Assets

microsoft
windows 10 1803
all versions
microsoft
windows 10 1809
all versions
microsoft
windows 10 1909
all versions
microsoft
windows 10 2004
all versions
microsoft
windows 10 20h2
all versions
microsoft
windows server 1909
all versions
microsoft
windows server 2004
all versions
microsoft
windows server 2019
all versions
microsoft
windows server 20h2
all versions

Mitigating Controls

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-787

Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.

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 mostly match
prevents

Secure-development practices (static analysis, bounds checking, code review) are the primary means of preventing out-of-bounds writes.

ID.RA-01 partial match
prevents

Vulnerability scanning and recording can discover out-of-bounds write flaws so they can be remediated.

PR.PS-02 partial match
prevents

Patching or replacing vulnerable software directly eliminates known instances of this coding weakness.

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.

finds

Security testing in development and acceptance can detect and prevent out-of-bounds write defects.

prevents

Secure development life cycle mandates practices that prevent out-of-bounds writes.

prevents

Application security requirements can specify bounds-checking and safe memory handling.

prevents

Secure architecture and engineering principles reduce the likelihood of buffer overflows.

prevents

Secure coding directly addresses out-of-bounds writes through language choice and coding standards.

prevents

Change management can enforce review gates that catch unsafe memory operations before deployment.

References