Advisory · CVE-2026-102863
Code injection in SharePoint Server can elevate privileges
Microsoft SharePoint Server has a code injection flaw an authorized attacker can use to elevate privileges over the network. Microsoft rates it CVSS 3.1 8.8.
- Vendor
- Microsoft
- Product
- Microsoft SharePoint Server
- Identifier / CWE
- CVE-2026-102863
CWE-94 - Action timing
- Immediate
Explain it like I’m five
Input an authorized user supplies can become code SharePoint runs, which is privilege elevation with extra steps removed.
- 01Attacker engages the component
A remote or authorized attacker sends crafted content or requests to Microsoft SharePoint Server.
- 02Weakness triggers
The component mishandles the input and the flaw takes effect.
- 03Impact lands
The attacker gains the execution, elevation, or access the flaw allows.
What happened
Microsoft disclosed CVE-2026-102863 in its October 2026 update guide: code injection (CWE-94) in Microsoft Office SharePoint can let an authorized attacker elevate privileges over the network. Microsoft’s affected data includes SharePoint Server Subscription Edition builds before 16.0.20326.20190.
Microsoft lists the affected releases and their patched build thresholds in its update guide. Apply the October 2026 security updates for your release rather than relying on a version guess here.
What to do
- Inventory every Microsoft SharePoint Server deployment, including test, training, and individually managed instances.
- Apply the vendor fix or upgrade exactly as directed in the linked vendor bulletin or advisory.
- Restrict network access to Microsoft SharePoint Server while remediation is underway, especially for internet-facing instances.
- Review application and server logs for privilege changes, new site administrators, and SharePoint actions by accounts outside their usual scope.
- Check for accounts, content, or configuration created outside normal change processes, and rotate exposed credentials where access cannot be ruled out.
- Verify the deployed version or patch level after remediation.
Management note
SharePoint holds the documents everyone forgot they shared. Privilege elevation there is a data-governance incident as much as a patch item.