CVE-2022-21907Public exploitNetwork attack vector

Unauthenticated code execution via Accept-Encoding double free

Published Jan 11, 2022 · Updated Jan 2, 2025

Remote code execution in the Windows HTTP Protocol Stack allows remote attackers to execute code via a crafted request to an HTTP.sys listener. The Accept-Encoding parser frees an unknown-coding list twice while processing a malformed header, and the demonstrated public proof of concept triggers a kernel crash. Reachability requires a listening HTTP.sys service; Windows Server 2019 and Windows 10 Version 1809 also require nondefault HTTP trailer support.

CVSS severity9.8
Critical
EPSS probability92.79%
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 the Windows HTTP Protocol Stack allows remote attackers to execute code via a crafted request to an HTTP.sys listener. The Accept-Encoding parser frees an unknown-coding list twice while processing a malformed header, and the demonstrated public proof of concept triggers a kernel crash. Reachability requires a listening HTTP.sys service; Windows Server 2019 and Windows 10 Version 1809 also require nondefault HTTP trailer support.

The record

CVE
CVE-2022-21907
Published
Jan 11, 2022
Updated
Jan 2, 2025
Vendor
Microsoft
Product
Windows Server 2019
Classifications
T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 11, 2022CVE publishedPublication date reported by the CVE source.
  2. Jan 2, 2025Record 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 <10.0.17763.2452

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Windows Server 2019version=10.0.17763.0 <10.0.17763.2452
Microsoft · Windows 10 Version 21H1version=10.0.0 <10.0.19043.1466
Microsoft · Windows 11 version 21H2version=10.0.0 <10.0.22000.434
Microsoft · Windows 10 Version 21H2version=10.0.19043.0 <10.0.19044.1466
Microsoft · Windows 10 Version 20H2version=10.0.0 <10.0.19042.1466
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.2452
Microsoft · Windows Server version 20H2version=10.0.0 <10.0.19042.1466
Microsoft · Windows Server 2022version=10.0.20348.0 <10.0.20348.469
Microsoft · Windows 10 Version 1809version=10.0.0 <10.0.17763.2452; version=10.0.17763.0 <10.0.17763.2452

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0NIST NVDAV:N/AC:L/Au:N/C:C/I:C/A:C

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1190Exploit Public-Facing Application

Public exploit references

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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