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Known Exploited Vulnerability
8.8
HIGH CVSS 3.1
CVE-2021-33742
Microsoft Windows MSHTML Platform Remote Code Execution Vulnerability - [Actively Exploited]
Description

Windows MSHTML Platform Remote Code Execution Vulnerability

INFO

Published Date :

June 8, 2021, 11:15 p.m.

Last Modified :

Oct. 29, 2025, 4:47 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]
CISA Notification
CISA KEV (Known Exploited Vulnerabilities)

For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.

Description :

Microsoft Windows MSHTML Platform contains an unspecified vulnerability that allows for remote code execution.

Required Action :

Apply updates per vendor instructions.

Notes :

https://nvd.nist.gov/vuln/detail/CVE-2021-33742

Affected Products

The following products are affected by CVE-2021-33742 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Microsoft windows_10
2 Microsoft windows_7
3 Microsoft windows_8.1
4 Microsoft windows_rt_8.1
5 Microsoft windows_server_2008
6 Microsoft windows_server_2012
7 Microsoft windows_server_2016
8 Microsoft windows_server_2019
9 Microsoft windows_10_1607
10 Microsoft windows_10_1809
11 Microsoft windows_10_20h2
12 Microsoft windows_10_1507
13 Microsoft windows_10_21h1
14 Microsoft windows_10_1909
15 Microsoft windows_10_2004
16 Microsoft windows_server_2012_r2
17 Microsoft windows_server_2008_r2
18 Microsoft windows_server_2008_sp2
: Total Affected Vendor : 1 | Products : 18
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 2.0 MEDIUM [email protected]
CVSS 3.1 HIGH [email protected]
CVSS 3.1 HIGH [email protected]
Solution
To address the remote code execution vulnerability, install the latest cumulative updates for your Windows operating system.
  • Apply the latest cumulative update.
  • Reboot the system if required.
Public PoC/Exploit Available at Github

CVE-2021-33742 has a 3 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2021-33742.

URL Resource
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33742 Patch Vendor Advisory
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33742 Patch Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33742 US Government Resource
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-33742 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-33742 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

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Birdo1221/UserAG-Changer

A Browser Extension That Changes Your User-agent, From Desktop to Macintosh to IOS + Custom UA

brower browser-extension chrome-extension css extension html javascript side-project spoofer spoofing user-agent useragent

JavaScript HTML CSS

Updated: 1 year, 3 months ago
0 stars 0 fork 0 watcher
Born at : July 17, 2024, 6:55 p.m. This repo has been linked 3 different CVEs too.
Profile Photo
Ostorlab/KEV

Ostorlab KEV: One-command to detect most remotely known exploitable vulnerabilities. Sourced from CISA KEV, Google's Tsunami, Ostorlab's Asteroid and Bug Bounty programs.

cisa-kev vulnerability 0day cisa exploits

Updated: 3 weeks ago
588 stars 42 fork 42 watcher
Born at : April 19, 2022, 8:58 a.m. This repo has been linked 1290 different CVEs too.
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yogsma/beacon23

Beacon23 - A Vulnerability Finder

Java

Updated: 4 years, 3 months ago
0 stars 0 fork 0 watcher
Born at : June 9, 2021, 2:53 a.m. This repo has been linked 1 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2021-33742 vulnerability anywhere in the article.

  • CybersecurityNews
Sophisticated DevilsTongue Windows Spyware Tracking Users Globally

The emergence of DevilsTongue marks a significant escalation in mercenary spyware capabilities, leveraging advanced Windows-based techniques to infiltrate high-value targets worldwide. First observed ... Read more

Published Date: Aug 06, 2025 (2 months, 3 weeks ago)

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2021-33742 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Modified Analysis by [email protected]

    Oct. 29, 2025

    Action Type Old Value New Value
    Added Reference Type CISA-ADP: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33742 Types: US Government Resource
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Oct. 22, 2025

    Action Type Old Value New Value
    Added Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33742
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Oct. 21, 2025

    Action Type Old Value New Value
    Removed Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33742
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Oct. 21, 2025

    Action Type Old Value New Value
    Added Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33742
  • Modified Analysis by [email protected]

    Feb. 24, 2025

    Action Type Old Value New Value
    Added CWE NIST CWE-787
    Removed CWE NIST CWE-119
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Feb. 04, 2025

    Action Type Old Value New Value
    Added CWE CWE-787
  • CVE Modified by af854a3a-2127-422b-91ae-364da2661108

    Nov. 21, 2024

    Action Type Old Value New Value
    Added Reference https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33742
  • Modified Analysis by [email protected]

    Jul. 29, 2024

    Action Type Old Value New Value
    Changed CPE Configuration OR *cpe:2.3:o:microsoft:windows_10:-:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_10:20h2:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_10:21h1:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_10:1607:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_10:1809:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_10:1909:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_10:2004:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_7:-:sp1:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_8.1:-:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_rt_8.1:-:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:* *cpe:2.3:o:microsoft:windows_server_2008:sp2:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2016:-:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2016:20h2:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2016:1909:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2016:2004:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2019:-:*:*:*:*:*:*:* OR *cpe:2.3:o:microsoft:windows_10_1507:*:*:*:*:*:*:*:* versions up to (excluding) 10.0.10240.18967 *cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:*:* versions up to (excluding) 10.0.14393.4467 *cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:*:* versions up to (excluding) 10.0.17763.1999 *cpe:2.3:o:microsoft:windows_10_1909:*:*:*:*:*:*:*:* versions up to (excluding) 10.0.18363.1621 *cpe:2.3:o:microsoft:windows_10_2004:*:*:*:*:*:*:*:* versions up to (excluding) 10.0.19041.1052 *cpe:2.3:o:microsoft:windows_10_20h2:*:*:*:*:*:*:*:* versions up to (excluding) 10.0.19042.1052 *cpe:2.3:o:microsoft:windows_10_21h1:*:*:*:*:*:*:*:* versions up to (excluding) 10.0.19043.1052 *cpe:2.3:o:microsoft:windows_7:-:sp1:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_8.1:-:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_rt_8.1:-:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:* *cpe:2.3:o:microsoft:windows_server_2008:sp2:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:* versions up to (excluding) 10.0.14393.4467 *cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:* versions up to (excluding) 10.0.17763.1999
  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • CVE Modified by [email protected]

    Dec. 30, 2023

    Action Type Old Value New Value
    Added CVSS V3.1 Microsoft Corporation AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
  • CWE Remap by [email protected]

    Aug. 08, 2023

    Action Type Old Value New Value
    Changed CWE CWE-681 CWE-119
  • CWE Remap by [email protected]

    Jul. 12, 2022

    Action Type Old Value New Value
    Changed CWE NVD-CWE-noinfo CWE-681
  • Initial Analysis by [email protected]

    Jun. 14, 2021

    Action Type Old Value New Value
    Added CVSS V2 Metadata Victim must voluntarily interact with attack mechanism
    Added CVSS V2 NIST (AV:N/AC:M/Au:N/C:P/I:P/A:P)
    Added CVSS V3.1 NIST AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
    Changed Reference Type https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33742 No Types Assigned https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33742 Patch, Vendor Advisory
    Added CWE NIST NVD-CWE-noinfo
    Added CPE Configuration OR *cpe:2.3:o:microsoft:windows_10:-:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_10:20h2:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_10:21h1:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_10:1607:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_10:1809:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_10:1909:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_10:2004:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_7:-:sp1:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_8.1:-:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_rt_8.1:-:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:* *cpe:2.3:o:microsoft:windows_server_2008:sp2:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2016:-:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2016:20h2:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2016:1909:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2016:2004:*:*:*:*:*:*:* *cpe:2.3:o:microsoft:windows_server_2019:-:*:*:*:*:*:*:*
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
Vulnerability Scoring Details
Base CVSS Score: 8.8
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact
Base CVSS Score: 6.8
Access Vector
Access Complexity
Authentication
Confidentiality Impact
Integrity Impact
Availability Impact
Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

68.07 }} 3.52%

score

0.98511

percentile