CVE-2021-31959 — Scripting Engine Memory Corruption Vulnerability

Critical CVSS 6.4 EPSS 0.0923 2021-07 archive

Executive Summary

None

Overview

6.4

CVSS MEDIUM

Critical

MS Severity

Not Exploited

MS Exploit Status

More Likely

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 0.0923 — 0.94892 percentile

NVD CVSS 6.4 MEDIUM — matches MSRC

CVSS Vector

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

ATTACK VECTOR

Network

ATTACK COMPLEXITY

High

PRIVILEGES REQUIRED

None

USER INTERACTION

Required

SCOPE

Unchanged

CONFIDENTIALITY

Low

INTEGRITY

High

AVAILABILITY

Low

EXPLOIT CODE MATURITY

Unproven

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 5.6

EPSS Score

0.0923

probability of exploitation in the next 30 days

0.94892 percentile - updated 2026-08-14

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: 6.4 Temporal: 5.6 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L/E:U/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: 6.4 Temporal: 5.6 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L/E:U/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: 6.4 Temporal: 5.6 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L/E:U/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: 6.4 Temporal: 5.6 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L/E:U/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 R2 for x64-based Systems Service Pack 1 5003667 (Monthly Rollup) 5003636 (IE Cumulative) Critical Remote Code Execution 5003233 5003165 Base: 6.4 Temporal: 5.6 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L/E:U/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: 6.4 Temporal: 5.6 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L/E:U/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: 6.4 Temporal: 5.6 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L/E:U/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

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

Ivan Fratric of Google Project Zero

References

MSRC Advisory MITRE NVD

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