CVE-2020-1126Network attack vector

Code execution via HEVC stream buffer overwrite

Published May 21, 2020 · Updated Aug 19, 2026

Out-of-bounds write in Windows Media Foundation allows remote attackers to execute code by opening crafted HEVC content. The HEVC stream parser fails to validate user-supplied data before writing past the end of an allocated buffer in the current process. Exploitation requires a user to open a malicious file or visit a malicious webpage, after which code runs with that user's rights.

CVSS severity8.8
High
EPSS probability4.01%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Windows Media Foundation allows remote attackers to execute code by opening crafted HEVC content. The HEVC stream parser fails to validate user-supplied data before writing past the end of an allocated buffer in the current process. Exploitation requires a user to open a malicious file or visit a malicious webpage, after which code runs with that user's rights.

The record

CVE
CVE-2020-1126
Published
May 21, 2020
Updated
Aug 19, 2026
Vendor
Microsoft
Product
Windows Server 2019
Classifications
CWE-787, T1204.002, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 21, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=10.0.17763.0 <publication

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Windows Server 2019version=10.0.17763.0 <publication
Microsoft · Windows 10 Version 1909version=10.0.0 <publication
Microsoft · Windows 10 Version 1803version=10.0.0 <publication
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.14393.0 <publication
Microsoft · Windows Server 2016version=10.0.14393.0 <publication
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <publication
Microsoft · Windows Server, version 1903 (Server Core installation)version=10.0.0 <publication
Microsoft · Windows 10 Version 1607version=10.0.14393.0 <publication
Microsoft · Windows Server, version 1803 (Server Core installation)version=10.0.0 <publication
Microsoft · Windows 10 Version 1709version=10.0.0 <publication
Microsoft · Windows 10 Version 1809version=10.0.0 <publication; version=10.0.17763.0 <publication
Microsoft · Windows Server, version 1909 (Server Core installation)version=10.0.0 <publication
Microsoft · Windows 10 Version 1903version=10.0.0 <publication

Published CVSS scores

9.3NIST NVDAV:N/AC:M/Au:N/C:C/I:C/A:C
8.8Microsoft CorporationCVSS:3.1/AV:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1204.002User Execution: Malicious File
T1204.001User Execution: Malicious Link

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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