Cyber Resilience

CVE-2021-28310

HighCISA KEVActive ExploitationEUVD Exploited

Published: 13 April 2021

Published
13 April 2021
Modified
30 October 2025
KEV Added
03 November 2021
Patch
CVSS Score v3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.5395 98.1th percentile
Risk Priority 68 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-28310 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, ranked in the top 1.9% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

The strongest mitigations our analysis identified are NIST 800-53 SI-16 (Memory Protection) and SI-2 (Flaw Remediation).

Deeper analysis

CVE-2021-28310 is a Win32k Elevation of Privilege Vulnerability affecting the Win32k component of Windows. It carries a CVSS 3.1 score of 7.8 and is associated with CWE-787, indicating an out-of-bounds write condition that can be triggered under local attack conditions.

An authenticated local attacker with low privileges can exploit the flaw without user interaction to elevate privileges on the affected system, resulting in full compromise of confidentiality, integrity, and availability within the local security boundary.

Microsoft has published official security guidance addressing the issue through its advisory portal, and the vulnerability appears in CISA's catalog of known exploited vulnerabilities, confirming observed in-the-wild exploitation activity.

EU & UK References

Vulnerability details

Win32k Elevation of Privilege Vulnerability

CWE(s)
KEV Date Added
03 November 2021

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

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

Mitigating Controls (NIST 800-53 r5) AI

prevent

Directly counters the out-of-bounds write (CWE-787) in Win32k by enforcing memory protections that block the kernel memory corruption used for privilege escalation.

prevent

Requires timely application of the vendor patch that eliminates the Win32k flaw, directly stopping the known in-the-wild exploitation path.

prevent

Restricts initial local account privileges so an attacker starts with fewer rights, limiting the impact even if the Win32k EoP is attempted.

References