CVE-2026-54992 Overview
CVE-2026-54992 is a heap-based buffer overflow vulnerability in the Windows Message Queuing (MSMQ) Queue Manager. The flaw allows an authenticated local attacker to corrupt heap memory and execute arbitrary code on the affected system. The vulnerability is tracked under [CWE-122] Heap-based Buffer Overflow and affects a broad range of Windows client and server operating systems.
Microsoft released a security advisory addressing the flaw. Successful exploitation results in full compromise of confidentiality, integrity, and availability on the target host, with the attacker gaining code execution in the context of the MSMQ service.
Critical Impact
Local attackers with low privileges can achieve arbitrary code execution on unpatched Windows systems running the Message Queuing service, leading to complete host compromise.
Affected Products
- Microsoft Windows 10 (versions 1607, 1809, 21H2, 22H2)
- Microsoft Windows 11 (versions 24H2, 25H2, 26H1)
- Microsoft Windows Server 2012, 2012 R2, 2016, 2019, 2022, and 2025
Discovery Timeline
- 2026-07-14 - CVE-2026-54992 published to NVD
- 2026-07-20 - Last updated in NVD database
Technical Details for CVE-2026-54992
Vulnerability Analysis
The vulnerability resides in the Windows Message Queuing Queue Manager component, which manages message queues for inter-process and inter-host communication. A heap-based buffer overflow occurs when the Queue Manager processes specially crafted input without validating buffer boundaries. This allows an attacker to write data beyond the allocated heap region, corrupting adjacent memory structures.
An attacker with local access and low privileges can trigger the overflow by interacting with the MSMQ service. Because MSMQ typically runs with elevated service privileges, successful exploitation grants the attacker code execution in a higher privilege context, effectively enabling local privilege escalation and full host compromise.
Root Cause
The root cause is improper bounds checking during message or queue metadata handling inside the MSMQ Queue Manager. Untrusted input sizes are used to copy data into a fixed-size heap allocation, producing an out-of-bounds write classified as [CWE-122].
Attack Vector
Exploitation requires local access to a system where the Message Queuing service is installed and running. The attacker submits crafted requests to the Queue Manager that trigger the overflow. No user interaction is required. The MSMQ service is not enabled by default on all Windows editions, which limits the attack surface to systems where administrators have explicitly installed or activated it.
No public proof-of-concept exploit is available at the time of publication, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.
Detection Methods for CVE-2026-54992
Indicators of Compromise
- Unexpected crashes or restarts of the mqsvc.exe process, which hosts the MSMQ Queue Manager
- Creation of anomalous child processes spawned by mqsvc.exe such as cmd.exe, powershell.exe, or rundll32.exe
- Windows Error Reporting entries referencing heap corruption in the Message Queuing service
- Unexpected loading of unsigned modules into the MSMQ service process
Detection Strategies
- Monitor process ancestry for mqsvc.exe spawning interactive shells or scripting hosts, which is not expected behavior
- Track service crash events (Event ID 7031, 7034) referencing the Message Queuing service
- Alert on new local accounts, scheduled tasks, or services created shortly after MSMQ service anomalies
- Correlate local privilege escalation indicators with active MSMQ activity on the host
Monitoring Recommendations
- Inventory all systems where the Message Queuing feature is installed and enabled, and reduce that footprint where the service is not required
- Enable command-line and process-creation auditing (Event ID 4688) with Sysmon coverage for mqsvc.exe
- Forward endpoint telemetry to a centralized analytics platform to enable correlation of service crashes with follow-on execution
- Baseline normal MSMQ behavior so deviations in child process activity are detected quickly
How to Mitigate CVE-2026-54992
Immediate Actions Required
- Apply the Microsoft security update referenced in the Microsoft Security Update CVE-2026-54992 advisory to all affected Windows client and server versions
- Identify hosts with the Message Queuing feature installed and prioritize patching those systems
- Disable or uninstall the MSMQ feature on systems that do not require it to eliminate the attack surface
- Restrict local logon rights on systems that host critical MSMQ workloads
Patch Information
Microsoft has published a security update for CVE-2026-54992 in its monthly update guide. Administrators should deploy the corresponding cumulative update for each affected Windows 10, Windows 11, and Windows Server release. Refer to the Microsoft Security Response Center advisory for the specific KB article and build numbers.
Workarounds
- Disable the Message Queuing Windows feature on systems that do not use it, which removes the vulnerable service entirely
- Block inbound TCP port 1801 at the host firewall on systems where MSMQ must remain installed but should not accept remote connections
- Enforce the principle of least privilege so that untrusted users cannot obtain local access to MSMQ hosts
# Disable the Message Queuing feature on Windows to remove the vulnerable component
Disable-WindowsOptionalFeature -Online -FeatureName MSMQ-Server -NoRestart
Disable-WindowsOptionalFeature -Online -FeatureName MSMQ-Container -NoRestart
# Verify the service state
Get-Service -Name MSMQ
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
