CVE-2021-33740

Code execution through user-opened media content

Published Jul 14, 2021 · Updated Aug 10, 2026

Remote code execution in Windows Media in affected Microsoft Windows releases allows attackers to execute code through user-opened content. Microsoft has not disclosed the affected codec, parser, file format, or unsafe operation performed on attacker-controlled media data. Exploitation requires user interaction and runs code in the security context of the application that processes the content.

CVSS severity7.8
High
EPSS probability2.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Remote code execution in Windows Media in affected Microsoft Windows releases allows attackers to execute code through user-opened content. Microsoft has not disclosed the affected codec, parser, file format, or unsafe operation performed on attacker-controlled media data. Exploitation requires user interaction and runs code in the security context of the application that processes the content.

The record

CVE
CVE-2021-33740
Published
Jul 14, 2021
Updated
Aug 10, 2026
Vendor
Microsoft
Product
Windows 10 Version 1507
Classifications
T1204.002, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 10, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0.10240.0 <10.0.10240.19003

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Microsoft · Windows 10 Version 1507version=10.0.10240.0 <10.0.10240.19003
Microsoft · Windows Server 2019version=10.0.17763.0 <10.0.17763.2061
Microsoft · Windows Server, version 2004version=10.0.0 <10.0.19041.1110
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.2061
Microsoft · Windows 10 Version 2004version=10.0.0 <10.0.19041.1110
Microsoft · Windows 10 Version 1809version=10.0.0 <10.0.17763.2061; version=10.0.17763.0 <10.0.17763.2061

Published CVSS scores

9.3NVDAV:N/AC:M/Au:N/C:C/I:C/A:C
7.8MicrosoftCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
7.8NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1204.002User Execution: Malicious File
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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