CVE-2023-21554Public exploitNetwork attack vector

Unauthenticated code execution via malformed MSMQ section sizes

Published Apr 11, 2023 · Updated Jan 23, 2025

Improper input validation in Microsoft Windows MSMQ allows remote attackers to execute code via malformed messages sent to TCP port 1801. CQmPacket trusts attacker-controlled section sizes when advancing the message-end pointer, then appends an OnDiskExtensionHeader beyond the allocated buffer. MSMQ must be enabled and reachable; successful exploitation runs code in the mqsvc.exe service process.

CVSS severity9.8
Critical
EPSS probability95.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Microsoft Windows MSMQ allows remote attackers to execute code via malformed messages sent to TCP port 1801. CQmPacket trusts attacker-controlled section sizes when advancing the message-end pointer, then appends an OnDiskExtensionHeader beyond the allocated buffer. MSMQ must be enabled and reachable; successful exploitation runs code in the mqsvc.exe service process.

The record

CVE
CVE-2023-21554
Published
Apr 11, 2023
Updated
Jan 23, 2025
Vendor
Microsoft
Product
Windows 10 Version 1507
Classifications
CWE-20, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 11, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 23, 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=10.0.10240.0 <10.0.10240.19869

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Windows 10 Version 1507version=10.0.10240.0 <10.0.10240.19869
Microsoft · Windows Server 2019version=10.0.17763.0 <10.0.17763.4252
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.14393.0 <10.0.14393.5850
Microsoft · Windows 11 version 21H2version=10.0.0 <10.0.22000.1817
Microsoft · Windows Server 2012 (Server Core installation)version=6.2.9200.0 <6.2.9200.24216
Microsoft · Windows Server 2012version=6.2.9200.0 <6.2.9200.24216
Microsoft · Windows 10 Version 21H2version=10.0.19043.0 <10.0.19044.2846
Microsoft · Windows Server 2016version=10.0.14393.0 <10.0.14393.5850
Microsoft · Windows Server 2008 R2 Service Pack 1version=6.1.7601.0 <6.1.7601.26466
Microsoft · Windows 10 Version 20H2version=10.0.0 <10.0.19042.2846
Microsoft · Windows Server 2008 R2 Service Pack 1 (Server Core installation)version=6.1.7601.0 <6.1.7601.26466
Microsoft · Windows 10 Version 22H2version=10.0.19045.0 <10.0.19045.2846
Microsoft · Windows Server 2012 R2 (Server Core installation)version=6.3.9600.0 <6.3.9600.20919
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.4252
Microsoft · Windows 11, version 22H2version=10.0.22621.0 <10.0.22621.1555
Microsoft · Windows 10 Version 1607version=10.0.14393.0 <10.0.14393.5850
Microsoft · Windows Server 2008 Service Pack 2version=6.0.6003.0 <6.0.6003.22015
Microsoft · Windows Server 2022version=10.0.20348.0 <10.0.20348.1668
Microsoft · Windows 10 Version 1809version=10.0.0 <10.0.17763.4252; version=10.0.17763.0 <10.0.17763.4252
Microsoft · Windows Server 2012 R2version=6.3.9600.0 <6.3.9600.20919
Microsoft · Windows Server 2008 Service Pack 2 (Server Core installation)version=6.0.6003.0 <6.0.6003.22015

Published CVSS scores

9.8Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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 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

CWE-20Improper Input Validation
T1210Exploitation of Remote Services

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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