Updates for SharePoint Server Subscription Edition (May 2026 CU)

17 May 2026    |    Comments   Comments: 0

A new cumulative update (May 2026 CU) has been released for SharePoint Server Subscription Edition.

SP Build:
16.0.19725.20280

Important before installation:

If you are upgrading from the September 2025 CU to a newer update, remove the NT AUTHORITY\SYSTEM account from the local WSS_WPG and IIS_IUSRS groups on every SharePoint server in the farm before installation, if it is a member. Otherwise, installation of the update may fail.

Starting with the March 2023 CU, updates for SharePoint Server Subscription Edition are released as a single package (known as an Uber package) containing both language-independent and language-dependent fixes. Only one package needs to be installed to fully update the server.

SharePoint Subscription Edition CU – KB articles describing the CU:

  • KB 5002863 – May 2026 Update for SharePoint Server Subscription Edition

SharePoint Server Subscription Edition CU – CU download links:

After installation, remember to run the SharePoint Products Configuration Wizard or the following command:

PSConfig.exe -cmd upgrade -inplace b2b -wait -cmd applicationcontent -install -cmd installfeatures -cmd secureresources -cmd services -install

Important notes

To speed up CU installation, I recommend following the guidance in How to speed up CU installation in SharePoint Server Subscription Edition.

The language you select when downloading the update does not matter because the same package is downloaded for every language.

Note for this CU:

KB 5002863: Install this CU on the release version of SharePoint Server Subscription Edition. If the farm uses SharePoint Workflow Manager, first install KB5002799.

Classic Workflow Manager requires enabling the following debug flag to remain usable:

$farm = Get-SPFarm
$farm.ServerDebugFlags.Add(53601)
$farm.update()
iisreset

Included fixes and improvements

The following overview summarizes the fixes and improvements in this CU based on the official Microsoft KB articles.

SharePoint Server Subscription Edition

KB 5002863 addresses remote code execution vulnerabilities in SharePoint Server. The KB references: CVE-2026-40357, CVE-2026-33112, CVE-2026-33110, CVE-2026-40368, CVE-2026-35439, CVE-2026-40367, CVE-2026-40365.

The unified package KB 5002863 brings these SharePoint Server Subscription Edition changes:

  • Enables keyboard navigation to column headers in the SPList Quick Edit view to improve accessibility.

  • Fixes an issue where pages cannot load because some user controls are classified as unsafe. After installation, explicitly trust the affected controls through the custom farm property AllowedTagPrefixesWhichAreNotWebControlsList.

  • Fixes an issue where changing settings on the Configure and Health SA page displays “Sorry, something went wrong”. It also fixes the incorrect PowerShell “Database already exists” error when only updating settings for an existing database.

  • Improves data ingestion throughput by raising the ingestion cache hit rate.

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