Microsoft’s December Updates Break Message Queuing
▼ Summary
– Microsoft’s December 2025 security updates are breaking Message Queuing (MSMQ) functionality, impacting enterprise applications and IIS websites.
– The issue affects specific Windows 10 and Server versions that installed certain KB updates, causing errors like inactive queues and misleading “insufficient resources” messages.
– The root cause is a security model change that now requires MSMQ users to have write access to a system folder normally restricted to administrators.
– Microsoft is investigating but has not provided a timeline for a fix, leaving admins to potentially roll back updates despite security risks.
– This follows a previous critical MSMQ vulnerability patched in 2023, highlighting ongoing security challenges with the service.
Microsoft’s latest round of security patches has inadvertently disrupted a core enterprise service, creating operational headaches for IT administrators. The company has acknowledged that the December 2025 security updates are causing Message Queuing (MSMQ) to malfunction, impacting a variety of business applications and websites hosted on Internet Information Services (IIS). This problem is specifically tied to the KB5071546, KB5071544, and KB5071543 updates deployed on Patch Tuesday, affecting systems running Windows 10 22H2, Windows Server 2019, and Windows Server 2016.
The symptoms of this failure are broad and disruptive. Administrators report that MSMQ queues have become inactive, while IIS websites are failing with confusing “insufficient resources” error messages. Applications are suddenly unable to write data to their queues. In some cases, systems are even generating misleading alerts about a lack of disk space or memory, despite having ample resources available. The root cause, as identified by Microsoft, lies in recent modifications to the MSMQ security model. These changes have altered the permissions on a crucial system directory, the `C:\Windows\System32\MSMQ\storage` folder.
Under the new configuration, MSMQ users now require write access to this folder, a level of permission typically reserved only for administrator accounts. Consequently, any attempt to send messages using MSMQ APIs is likely to fail with resource-related errors. This configuration problem also extends to clustered MSMQ environments that are under significant operational load. It is important to note that systems where users are logged in with full administrative rights are not experiencing these issues, as those accounts already possess the necessary permissions.
Message Queuing is an optional component available across Windows operating systems, providing essential network communication functions for distributed applications. It is a staple in many corporate IT environments for enabling reliable messaging between different software components. Microsoft has stated it is actively investigating the situation but has not offered a specific timeline for a resolution. The company has not clarified whether it will address the problem in its next scheduled monthly update or issue an out-of-band emergency fix.
For administrators dealing with immediate outages, the most direct workaround involves rolling back the problematic security updates. However, this action carries significant risk, as it would leave systems vulnerable to the security flaws those patches were designed to fix. This incident highlights the delicate balance between securing systems and maintaining stability. It is a stark reminder of the potential for widespread disruption when a critical vulnerability like CVE-2023-21554, which targeted the MSMQ service for remote code execution, necessitates urgent security model changes that can have unintended consequences.
(Source: Bleeping Computer)