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Exchange Server 2016 CU23 Exchange Server 2016 CU23 ESU only Hotfix update

KB5050674

KB5050674

Hotfix update for Exchange Server 2016 CU23, April 2025

In short

This hotfix for Exchange Server 2016 CU23 addresses one Important-severity vulnerability. It is available only to organizations in the Extended Security Update program.

Does it affect you? Applies to: Organizations enrolled in the Extended Security Update program that run Exchange Server 2016 CU23.

Build
15.1.2507.55
Servicing branch
CU23
Security
1 fixed

For servers running Cumulative Update 23: each cumulative update gets its own update. Support for this version ended on October 14, 2025: Microsoft releases this update only to organizations enrolled in the Extended Security Update (ESU) program, not through Microsoft Update. The others should move to Exchange Server Subscription Edition. Which version am I on?

In detail

  • Security Addresses one Important-severity vulnerability. The dossier does not identify its CVE or affected component.

Technical details

Data sheet · Security · Downloads · Components Click to collapse or expand

Data sheet

Released
2025-04-18
Classification
Updates
Type
Cumulative update
Servicing branch
CU23
Replaces
KB5049233
Replaced by
KB5057653
VersionBuildChannel
2016 15.1.2507.55 General availability

Security

1 vulnerability fixed
1 important
VulnerabilitySeverityCVSS
CVE-2025-53786
Microsoft Exchange Server Hybrid Deployment Elevation of Privilege Vulnerability
 Important 8.0

Sources

Updated
Checked automatically: 8 of 8 checks passed · compared with Microsoft's page on Nov 8, 2026
  • Quotes found in the official pages: passed
  • Numbers found in the sources: passed
  • Vulnerabilities from the dossier only: passed
  • Links to allowed domains only: passed
  • Every official change covered: passed
  • Readable plain text: passed
  • Changes confirmed by the file list: passed
  • Sources agree: passed

A second AI read the text against the sources: correctness 5/5, clarity 5/5, completeness 5/5. How we work

Published by The Update Bureau. Written with AI from Microsoft's own documents, checked by rules and a second AI. How we work · Report a mistake