OnlyFm252
Windows MSHTML Platform

CVE-2021-33742 — Windows MSHTML Platform Remote Code Execution Vulnerability

Critical CVSS 7.5 EPSS 0.59139 ⚠️ Exploited in the wild 2021-07 archive

Executive Summary

None

Overview

7.5
CVSS HIGH
Critical
MS Severity
Exploited
MS Exploit Status
Exploitation Detected
MS Exploit Likelihood
Category Remote Code Execution
Released Jul 13 2021
Last Updated Jul 13 2021
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.59139 — 0.98993 percentile
NVD CVSS 7.5 HIGH — matches MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
ATTACK VECTOR
Network
ATTACK COMPLEXITY
High
PRIVILEGES REQUIRED
None
USER INTERACTION
Required
SCOPE
Unchanged
CONFIDENTIALITY
High
INTEGRITY
High
AVAILABILITY
High
EXPLOIT CODE MATURITY
Functional
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 7.0

EPSS Score

0.59139
probability of exploitation in the next 30 days
0.98993 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 5003687 (Security Update) Critical Remote Code Execution Yes
Windows 10 for x64-based Systems 5003687 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 1607 for 32-bit Systems 5003638 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 1607 for x64-based Systems 5003638 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 1809 for 32-bit Systems 5003646 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 1809 for ARM64-based Systems 5003646 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 1809 for x64-based Systems 5003646 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 1909 for 32-bit Systems 5003635 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 1909 for ARM64-based Systems 5003635 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 1909 for x64-based Systems 5003635 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 2004 for 32-bit Systems 5003637 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 2004 for ARM64-based Systems 5003637 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 2004 for x64-based Systems 5003637 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 20H2 for 32-bit Systems 5003637 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 20H2 for ARM64-based Systems 5003637 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 21H1 for 32-bit Systems 5003637 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 21H1 for ARM64-based Systems 5003637 (Security Update) Critical Remote Code Execution Yes
Windows 10 Version 21H1 for x64-based Systems 5003637 (Security Update) Critical Remote Code Execution Yes
Windows 7 for 32-bit Systems Service Pack 1 5003667 (Monthly Rollup) 5003636 (IE Cumulative) Critical Remote Code Execution 5003233 5003165 Base: 7.5 Temporal: 7.0 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C 6.1.7601.25632 Yes 5003667 Windows 7 for x64-based Systems Service Pack 1 5003667 (Monthly Rollup) 5003636 (IE Cumulative) Critical Remote Code Execution 5003233 5003165 Base: 7.5 Temporal: 7.0 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C 6.1.7601.25632 Yes 5003667 Windows 8.1 for 32-bit systems 5003671 (Monthly Rollup) 5003636 (IE Cumulative) Critical Remote Code Execution 5003209 5003165 Base: 7.5 Temporal: 7.0 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C 6.3.9600.20045 1.0.0.0 Yes 5003671 Windows 8.1 for x64-based systems 5003671 (Monthly Rollup) 5003636 (IE Cumulative) Critical Remote Code Execution 5003209 5003165 Base: 7.5 Temporal: 7.0 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C 6.3.9600.20045 1.0.0.0 Yes 5003671 Windows RT 8.1 5003671 (Monthly Rollup) Critical Remote Code Execution Yes
Windows Server 2008 for 32-bit Systems Service Pack 2 5003636 (IE Cumulative) 5003661 (Monthly Rollup) Critical Remote Code Execution 5003165 5003210 Base: 7.5 Temporal: 7.0 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C 6.0.6003.21137 Yes 5003661 Windows Server 2008 for x64-based Systems Service Pack 2 5003636 (IE Cumulative) 5003661 (Monthly Rollup) Critical Remote Code Execution 5003165 5003210 Base: 7.5 Temporal: 7.0 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C 6.0.6003.21137 Yes 5003661 Windows Server 2008 R2 for x64-based Systems Service Pack 1 5003667 (Monthly Rollup) 5003636 (IE Cumulative) Critical Remote Code Execution 5003233 5003165 Base: 7.5 Temporal: 7.0 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C 6.1.7601.25632 Yes 5003667 Windows Server 2012 5003636 (IE Cumulative) 5003697 (Monthly Rollup) Critical Remote Code Execution 5003165 5003208 Base: 7.5 Temporal: 7.0 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C 1.0.0.0 6.2.9200.23372 Yes 5003697 Windows Server 2012 R2 5003671 (Monthly Rollup) 5003636 (IE Cumulative) Critical Remote Code Execution 5003209 5003165 Base: 7.5 Temporal: 7.0 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C 6.3.9600.20045 1.0.0.0 Yes 5003671 Windows Server 2016 5003638 (Security Update) Critical Remote Code Execution Yes
Windows Server 2019 5003646 (Security Update) Critical Remote Code Execution Yes

Patches

6 patches
Article Type Restart
5003687 Security Update Yes
5003638 Security Update Yes
5003646 Security Update Yes
5003635 Security Update Yes
5003637 Security Update Yes
5003671 Monthly Rollup Yes

Known Exploits

Acknowledgments

Clément Lecigne of Google’s Threat Analysis Group

On This Page