7.5

CVE-2021-33742: Microsoft Windows MSHTML Platform Remote Code Execution Vulnerability

CVSS: 7.5v3.1HighKEVAnalyzed
Published 08-06-2021Last modified 21-10-2025
Open JSON

Vulnerability summary

CVE-2021-33742 is a high (CVSS 7.5) Out-of-bounds Write vulnerability in Microsoft Windows. It is known to be exploited: CISA lists it, first on 03-11-2021. EPSS estimates a 59.41% chance of exploitation in the next 30 days, higher than 99.1% of scored vulnerabilities.

Overall risk
85/100
0100
Critical · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
59.41%
0%100%
Critical · 0.00 pp in 30 days
KEVListedCISA
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 08-06-2021
    PublishedVulnerability first disclosed.
  2. 03-11-2021
    Added to CISA KEVMicrosoft Windows MSHTML Platform Remote Code Execution Vulnerability
  3. 17-11-2021
    CISA remediation dueApply updates per vendor instructions.
  4. 21-10-2025
    Last modifiedVulnerability information updated.

Description

Windows MSHTML Platform Remote Code Execution Vulnerability

CVSS metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

59.41%

Chance of exploitation in the next 30 days

Percentile

99%

Versus all other CVEs

30-day change

0.00 pp

From 59.41% on 19-09-2026

19-09-202619-10-2026
EPSS score
59.41%

Known exploited

Compare KEV catalogs
CISA KEVListed
Added
03-11-2021
Federal due date
17-11-2021

CISA required action

Apply updates per vendor instructions. nvd.nist.gov/vuln/detail/CVE-2021-33742

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Microsoft26 products

1 vendor · 26 products

References

2 links