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CVE

CVE-2021-33742

Microsoft Windows MSHTML Platform Remote Code Execution Vulnerability

Windows MSHTML Platform Remote Code Execution Vulnerability.

HIGH · CVSS 7.5 ⚠ CISA KEV EPSS 0.72116
Act now
  • Listed on CISA KEV (known exploited in the wild)
  • SSVC exploitation status: active
  • EPSS ≥ 0.50 - high probability of exploitation in the next 30 days
  • EPSS percentile: top 1% of all CVEs by exploitation likelihood
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬢

Required Remediation

Apply updates per vendor instructions.

⬡

Weakness Classification

CWE-787Out-of-bounds Write
CWE-787Out-of-bounds Write
▤

Affected Products & Versions

14
microsoft windows 10 1507< 10.0.10240.18967
microsoft windows 10 1607< 10.0.14393.4467
microsoft windows 10 1809< 10.0.17763.1999
microsoft windows 10 1909< 10.0.18363.1621
microsoft windows 10 2004< 10.0.19041.1052
microsoft windows 10 20h2< 10.0.19042.1052
microsoft windows 10 21h1< 10.0.19043.1052
microsoft windows 7all versions
◈

Detection Rules (IDS/IPS)

1
et-openET EXPLOIT IE MSHTML Out-of-Bounds Write Inbound (CVE-2021-33742)attempted-admin
Open rulesets (ET Open, Snort Community, abuse.ch) link to source. Commercial rulesets are reference-only.
▣

Scoring & Timeline

7.5
HIGH · CVSS v3.1 · secure@microsoft.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD08 Jun 2021 · 11:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
active
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

2
cisaKEV-CVE-2021-33742
msrcCVE-2021-33742Remote Code Execution
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33742PatchVendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33742US Government Resource
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