CVE-2021-34534 — Windows MSHTML Platform Remote Code Execution Vulnerability

Executive Summary

None

Overview

6.8

CVSS MEDIUM

Critical

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Remote Code Execution

Released Aug 10 2021

Last Updated Aug 10 2021

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.01915 — 0.77168 percentile

NVD CVSS 6.8 MEDIUM — matches MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C

ATTACK VECTOR

Network

ATTACK COMPLEXITY

High

PRIVILEGES REQUIRED

None

USER INTERACTION

Required

SCOPE

Unchanged

CONFIDENTIALITY

High

INTEGRITY

High

AVAILABILITY

None

EXPLOIT CODE MATURITY

Unproven

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 5.9

EPSS Score

0.01915

probability of exploitation in the next 30 days

0.77168 percentile - updated 2026-06-21

View on FIRST.org

Affected Products

21 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 for 32-bit Systems	`5005040 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 for x64-based Systems	`5005040 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1607 for 32-bit Systems	`5005043 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1607 for x64-based Systems	`5005043 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1809 for 32-bit Systems	`5005030 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1809 for ARM64-based Systems	`5005030 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1809 for x64-based Systems	`5005030 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1909 for 32-bit Systems	`5005031 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1909 for ARM64-based Systems	`5005031 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 1909 for x64-based Systems	`5005031 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 2004 for 32-bit Systems	`5005033 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 2004 for ARM64-based Systems	`5005033 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 2004 for x64-based Systems	`5005033 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 20H2 for 32-bit Systems	`5005033 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 20H2 for ARM64-based Systems	`5005033 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 20H2 for x64-based Systems	`5005033 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H1 for 32-bit Systems	`5005033 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H1 for ARM64-based Systems	`5005033 (Security Update)`	Critical	Remote Code Execution	Yes
Windows 10 Version 21H1 for x64-based Systems	`5005033 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2016	`5005043 (Security Update)`	Critical	Remote Code Execution	Yes
Windows Server 2019	`5005030 (Security Update)`	Critical	Remote Code Execution	Yes

Patches

5 patches

Article	Type	Restart
`5005040`	Security Update	Yes
`5005043`	Security Update	Yes
`5005030`	Security Update	Yes
`5005031`	Security Update	Yes
`5005033`	Security Update	Yes

Known Exploits

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

Yuki Chen

References

MSRC Advisory MITRE NVD