SharePoint Update — Content Security Policy (CSP) Changes
Microsoft will begin rolling out an important security update to SharePoint Online starting March 1st, 2026, related to script loading policies (Content Security Policy — CSP).
This evolution strengthens Microsoft 365 security practices.
It does not introduce risk when environments are properly prepared.
You'll find more information about this topic in the following article published by Microsoft :
SharePoint Online Content Security Policy (CSP): Enforcement Dates and Guidance
This article explains:
What is changing
Potential impacts
Recommended actions
How to verify your environment
Key Takeaways
This is a planned Microsoft security evolution
It affects how SharePoint authorizes script execution
No complex action is required in most cases
A simple verification is recommended to ensure future deployments run smoothly
Context — What is Content Security Policy (CSP)?
Content Security Policy (CSP) is a browser security mechanism used by SharePoint to control which sources are allowed to load code (JavaScript, styles, etc.).
Its objectives are to:
Prevent malicious script execution
Reduce web-based attack risks
Strengthen overall security compliance
Microsoft is tightening these controls in 2026 by enforcing stricter validation rules.
What Is Changing
With this update:
Scripts from non-approved sources may be blocked
Some non-compliant inline scripts may be rejected
Custom SharePoint solutions relying on external resources could be affected
For end users, in non-compliant environments this may result in:
Components not displaying properly
Error messages appearing instead of content
Important Focus — Trusted Script Sources Limit
SharePoint now enforces a limit of:
-> Maximum 300 trusted script source entries per tenant
Each solution deployment or version can add entries to this list.
Without periodic cleanup:
Future deployments may be blocked
Some updates may fail
This is currently the primary item to monitor.
Recommended Preventive Action
We recommend performing a quick verification:
1️⃣ Go to SharePoint Admin Center
2️⃣ Navigate to Advanced > Script sources

3️⃣ Check:
Total number of entries
Presence of outdated or unused versions
4️⃣ Remove obsolete entries if necessary
This helps ensure:
A clean environment
Smooth future deployments
Compliance with the new security policy
Optional — Testing CSP Behavior (Technical Profiles)
Before full enforcement, you can simulate strict CSP behavior on a page:
1️⃣ Add to the URL of a page containing components:
?csp=enforce
2️⃣ Clear browser cache
3️⃣ Refresh the page
Results:
If compliant → components display normally
If not → errors appear
⚠️ This test only affects your session.
Our Commitment
We actively monitor Microsoft platform evolutions and continuously adapt our solutions to maintain compatibility with updated security requirements.
This transition contributes to:
Improved stability
Stronger security
Continued solution reliability
Need Assistance?
If you would like to:
Validate your configuration
Better understand your situation
Receive guidance on verification
Our support team is available to assist you.
Feel free to reach out via our form : contact Jint support.
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