Windows Message Queuing: Heap-based buffer overflow enables remote code execution
Summary
The Queue Manager component of Windows Message Queuing (MSMQ) in supported Windows 10, Windows 11 and Windows Server versions contains a heap-based buffer overflow (CWE-122). An unauthenticated attacker on the network can execute code with high impact on confidentiality, integrity and availability, but attack complexity is high. Only systems with MSMQ installed are affected.
Affected
- Windows 10 Version 1607 (builds before 10.0.14393.9688)
- Windows 10 Version 1809 (builds before 10.0.17763.9487)
- Windows 10 Version 21H2 (builds before 10.0.19044.7846)
- Windows 10 Version 22H2 (builds before 10.0.19045.7846)
- Windows 11 Version 23H2 (builds before 10.0.22631.7711)
- Windows 11 Version 24H2 (builds before 10.0.26100.9974)
- Windows 11 Version 25H2 (builds before 10.0.26200.9974)
- Windows 11 Version 26H1 (builds before 10.0.28000.3501)
- Windows 11 Version 26H2 (builds before 10.0.26300.9974)
- Windows Server 2016, including Server Core (builds before 10.0.14393.9688)
- Windows Server 2019, including Server Core (builds before 10.0.17763.9487)
- Windows Server 2022 (builds before 10.0.20348.5870)
Fixed in
- Install the November 2026 Windows security update or a later cumulative update.
- Fixed builds per the CNA record are listed as the first builds that are not affected in the Affected section.
- Windows 11 23H2: KB5131087 (build 10.0.22631.7711)
- Windows 11 24H2/25H2: KB5132061 (builds 10.0.26100.9974 / 10.0.26200.9974)
Workaround
Unknown. No Microsoft workaround is documented. If MSMQ is not required on a host, remove the feature. If it is required, restrict access to TCP port 1801 to the hosts that need it.
Exploitation
- No exploitation known at the time of data collection.
- CISA SSVC: exploitation none, not automatable, technical impact total.
- CVSS temporal exploit code maturity: Unproven (E:U).
- No public proof-of-concept found in the sources reviewed.
Our recommendation
- Install the November 2026 Windows security update on all affected systems, starting with MSMQ servers.
- Check whether MSMQ is installed (Windows feature or server role) and identify these hosts.
- Make sure TCP port 1801 and MSMQ traffic are not reachable from the internet or untrusted networks.
- Monitor the MSRC entry and CISA KEV for changes.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Critical
- Impact
- Remote code execution – Windows Message Queuing Queue Manager
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5131291, KB5131085, KB5131096, KB5131090, KB5131087, KB5132061
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-109459 msrc.microsoft.com
- CVE Record CVE-2026-109459 www.cve.org
- Strix: CVE-2026-109459 www.strix.ai
- Microsoft KB5131087: Windows 11 23H2 security update support.microsoft.com
- Microsoft KB5132061: Windows 11 24H2/25H2/26H2 security update support.microsoft.com
- Microsoft Windows message center (release health) learn.microsoft.com
- Senserva: KB5131096 (Windows 10 21H2) senserva.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 11 Nov 2026, 01:46.
Original description (NVD)
Heap-based buffer overflow in Windows Message Queuing Queue Manager allows an unauthorized attacker to execute code over a network.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
Affected? We can help.
We check whether your systems are affected, install updates and close the gap – continuously with the System Health Checker if you wish.