CVE-2026-55016 in Microsoft SharePoint Server
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an authorized attacker to perform spoofing over a network.
Quick answer
Microsoft SharePoint Server should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- Microsoft SharePoint Enterprise Server 2016 before 16.0.5561.1001
- Microsoft SharePoint Server 2019 before 16.0.10417.20175
- Microsoft SharePoint Server Subscription Edition before 16.0.19725.20434
Fixed versions
- SharePoint Server 2016 16.0.5561.1001 or later
- SharePoint Server 2019 16.0.10417.20175 or later
- SharePoint Subscription Edition 16.0.19725.20434 or later
How to fix it
Update Microsoft SharePoint Server. The old server can let an attacker spoof pages, read paths, or run code, depending on the CVE.
- Back up the SharePoint farm and databases.
- Install the Microsoft security update for your SharePoint branch.
- Run the SharePoint configuration wizard if Microsoft requires it.
- Review recent page, login, and admin activity.
Scan now. Google sign-in is only needed to unlock fix guidance.
Verify the fix
- Confirm the SharePoint build is at the fixed build or later.
- Scan again and confirm CVE-2026-55016 is gone.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-55016?
Microsoft SharePoint Server versions listed as affected should be reviewed: Microsoft SharePoint Enterprise Server 2016 before 16.0.5561.1001, Microsoft SharePoint Server 2019 before 16.0.10417.20175, Microsoft SharePoint Server Subscription Edition before 16.0.19725.20434.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.