CVE-2021-34521

User-assisted arbitrary code execution

Published Jul 14, 2021 · Updated Aug 10, 2026

Remote code execution in Microsoft Raw Image Extension on affected Windows builds allows local users to run code through a crafted image. Microsoft has not published the decoder locus or the incorrect operation performed on image data. Exploitation requires user interaction with attacker-supplied content, and successful execution occurs in the affected user's context.

CVSS severity7.8
High
EPSS probability2.36%
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 Microsoft Raw Image Extension on affected Windows builds allows local users to run code through a crafted image. Microsoft has not published the decoder locus or the incorrect operation performed on image data. Exploitation requires user interaction with attacker-supplied content, and successful execution occurs in the affected user's context.

The record

CVE
CVE-2021-34521
Published
Jul 14, 2021
Updated
Aug 10, 2026
Vendor
Microsoft
Product
Windows 10 Version 21H1
Classifications
T1204.002
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=10.0.0 <10.0.19043.1110

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Microsoft · Windows 10 Version 21H1version=10.0.0 <10.0.19043.1110
Microsoft · Windows 10 Version 1909version=10.0.0 <10.0.18363.1679
Microsoft · Windows 10 Version 20H2version=10.0.0 <10.0.19042.1110
Microsoft · Windows Server version 20H2version=10.0.0 <10.0.19042.1110

Published CVSS scores

7.8Microsoft CorporationCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 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

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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