CVE-2021-33742 kev in the critical feed json
Windows MSHTML Platform Remote Code Execution Vulnerability
published 2021-06-08 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-20419
- cvss
- 8.8
- version 3.1, CNA
- cisa kev
- Exploited
- added 2021-11-03
- epss
- 59.4%
- EPSS 59.4% chance of exploitation in 30 days, percentile 99.1%
- public exploits
- 0
- none known
Summary
Windows MSHTML Platform Remote Code Execution Vulnerability
Patch / fix
cisa required action Apply updates per vendor instructions.
- Microsoft Windows 10 Version 1809 10.0.17763.1999
- Microsoft Windows Server 2019 10.0.17763.1999
- Microsoft Windows 10 Version 1909 10.0.18363.1621
- Microsoft Windows 10 Version 21H1 10.0.19043.1052
- Microsoft Windows 10 Version 2004 10.0.19041.1052
- Microsoft Windows 10 Version 20H2 10.0.19042.1052
- Microsoft Windows 10 Version 1507 10.0.10240.18967
- Microsoft Windows 10 Version 1607 10.0.14393.4467
- Microsoft Windows Server 2016 10.0.14393.4467
- Microsoft Windows 7 6.1.7601.25632
- Microsoft Windows 7 Service Pack 1 6.1.7601.25632
- Microsoft Windows 8.1 1.0.0.0, 6.3.9600.20045
- Microsoft Windows Server 2008 Service Pack 2 6.0.6003.21137
- Microsoft Windows Server 2008 Service Pack 2 6.0.6003.21137
- Microsoft Windows Server 2008 R2 Service Pack 1 6.1.7601.25632
- Microsoft Windows Server 2012 1.0.0.0, 6.2.9200.23372
- Microsoft Windows Server 2012 R2 1.0.0.0, 6.3.9600.20045
Timeline
- Found exploited as a 0-day (Project Zero)
- 0-day patched (Project Zero)
- Published
- Added to CISA KEV
- CISA patch deadline
- CISA SSVC: exploitation active
Known exploited
- Added
- 5 y ago
- Patch by
- 2021-11-17 (4 y ago)
- Ransomware
- Not known
- Required action
- Apply updates per vendor instructions.
- Vendor, product
- Microsoft, Windows
- CISA name
- Microsoft Windows MSHTML Platform Remote Code Execution Vulnerability
Zero-day
Detected in real attacks while still unknown to the vendor and the public, per Google Project Zero's 0day In-the-Wild tracker.
- Found
- 2021-06-03
- Patched
- 2021-06-08
- Details
- project zero root cause analysis
CISA SSVC
- Exploitation
- Active, exploited in the wild
- Automatable
- no
- Technical impact
- total
- Assessed
- 21 mo ago
Exploit prediction
59.41% chance of exploitation in the next 30 days, higher than 99.1% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.5 | 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 |
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H |
| CNA | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H |
| NVD | 2.0 | 6.8 | AV:N/AC:M/Au:N/C:P/I:P/A:P |
Affected products
- Microsoft Windows 10 Version 1809
- Microsoft Windows Server 2019
- Microsoft Windows 10 Version 1909
- Microsoft Windows 10 Version 21H1
- Microsoft Windows 10 Version 2004
- Microsoft Windows 10 Version 20H2
- Microsoft Windows 10 Version 1507
- Microsoft Windows 10 Version 1607
- Microsoft Windows Server 2016
- Microsoft Windows 7
- Microsoft Windows 7 Service Pack 1
- Microsoft Windows 8.1
- Microsoft Windows Server 2008 Service Pack 2
- Microsoft Windows Server 2008 Service Pack 2
- Microsoft Windows Server 2008 R2 Service Pack 1
- Microsoft Windows Server 2012
- Microsoft Windows Server 2012 R2
Classification
- Weakness
-
- CWE-787 Out-of-bounds Write
References
-
portal.msrc.microsoft.com
/en-US/security-guidance/advisory/CVE-2021-33742
patch, vendor-advisory
-
cisa.gov
/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33742
government-resource, us-government-resource
Sources
- CVE List CVE-2021-33742
- NVD CVE-2021-33742
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.