CVE-2026-55052 sharepoint server vulnerability

Who is affected

How to fix it

Missing authorization in Microsoft Office SharePoint allows an authorized attacker to elevate privileges over a network. This is a high SharePoint Server issue involving privilege escalation. Patch SharePoint Server with the latest Microsoft security update for the affected farm version. Because SharePoint is often exposed to many users, also review access, custom pages, and server logs while the update is rolled out.

1. Identify every SharePoint Server farm and server affected by CVE-2026-55052.
2. Back up the farm, databases, and configuration before patching.
3. Install the latest Microsoft SharePoint Server security update on every farm server.
4. Run the SharePoint configuration wizard or required post-update steps after installation.
5. Restrict SharePoint admin access and remove unnecessary external exposure while patching.
6. Review IIS, ULS, and SharePoint audit logs for unusual requests or permission changes.
7. If exploitation is suspected, isolate the farm path and start incident response review.

Verify the fix

• Confirm every SharePoint server reports the updated build level.
• Check that the farm patch status is healthy for CVE-2026-55052.
• Open key SharePoint sites and confirm search, documents, workflows, and sign-in still work.
• Review IIS and ULS logs again after patching for suspicious activity.
• Save the build number, farm health check, and log review evidence.

Related categories

Trusted references

FAQ