If you manage Windows systems in an enterprise, you know that applying security patches is non-negotiable. But you also know something equally uncomfortable: sometimes, updates are what cause the problem. That’s exactly what’s happening after the latest Patch Tuesday in December 2025.
Microsoft has officially urged IT admins to contact its enterprise support to mitigate a known bug that’s causing outages in corporate apps and IIS-based websites. At TecnetOne, we break down what’s happening, why it’s serious, and what to do if your infrastructure is affected.
The issue is tied to Microsoft Message Queuing (MSMQ), an optional Windows service widely used in enterprise environments to let applications communicate reliably over a network.
After installing the following December 2025 security updates:
many organizations began experiencing anomalies and serious production failures. The most affected systems are:
If your company relies on IIS, internal business apps, or queue-based architectures, this bug could impact you directly.
Microsoft has made it clear: this is not an issue for home users, but a real concern for managed enterprise environments. And that’s already a red flag.
Reported symptoms include:
In other words, your infrastructure may look fine—but stop working.
Read more: Microsoft Patch Tuesday December 2025: 57 Vulnerabilities Fixed
The failure is directly related to changes in MSMQ’s security model introduced in the recent patches.
Microsoft altered NTFS permissions on a critical system folder:
C:\Windows\System32\MSMQ\storage
After the patch, MSMQ users need write access to this folder. The problem is that, by design, this directory is often restricted to administrators only.
This creates a classic clash between security and functionality:
What makes this bug particularly tricky is that it doesn't point directly to a permissions issue—it manifests as what seems like infrastructure failure.
Microsoft acknowledges the problem and says it’s investigating. However, you should note:
Instead of releasing official guidance, Microsoft is asking enterprises to contact their support channels to get specific mitigation steps.
This strongly suggests the workaround may involve sensitive changes—like permission adjustments or system tweaks not meant to be applied blindly.
If your environment is affected, you essentially have three imperfect options:
1. Contact Microsoft Support (Recommended)
Microsoft is offering a temporary workaround, but only through enterprise support. This minimizes the risk of applying insecure or incorrect fixes.
2. Manually Adjust Permissions (Use Extreme Caution)
Some IT teams have found that adding write permissions to the MSMQ folder helps. However, doing this incorrectly can introduce serious security risks.
3. Roll Back the Updates
This is the most drastic—and risky—option. Uninstalling security patches exposes your systems, especially internet-facing servers, to known vulnerabilities.
At TecnetOne, we strongly advise against rash decisions. Every environment is different, and generic fixes can often do more harm than good.
This isn't an isolated case. In July 2025, Microsoft also advised enterprises to contact support for a critical issue causing:
It’s a pattern: essential patches, deep security changes, and serious side effects in complex environments.
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Beyond this specific bug, this case offers important takeaways for any business running Windows infrastructure:
TecnetOne recommends these concrete actions:
These incidents can’t always be avoided—but they can be managed better when you're prepared.
Microsoft is right to push for updates. But this case proves that updating without a strategy is just as dangerous as not patching at all.
If your infrastructure depends on Windows Server, IIS, and services like MSMQ, this is a clear warning: cybersecurity and operations must go hand in hand.
At TecnetOne, we believe true resilience doesn’t come from avoiding mistakes—but from detecting fast, understanding the impact, and responding with clarity. Because in enterprise IT, the biggest risk isn’t technical failure—it’s not knowing how to respond when it happens.