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Exchange Server 2016 / 2019 CU14 Exchange Server 2016 / 2019 CU14 ESU only Hotfix update

KB5037224

KB5037224: Hotfix update for Exchange Server 2016 CU14, April 2024. ECC certificates added; CU14 adds HMA for OWA and ECP

In short

Adds Elliptic Curve Cryptography certificate support to Exchange 2016 and 2019, and Hybrid Modern Authentication for OWA and ECP on Exchange 2019 CU14. It also includes one Important security fix and resolves seven listed issues.

Does it affect you? Applies to: Organizations enrolled in the Extended Security Update program running Exchange Server 2019 CU14 or CU13, or Exchange Server 2016 CU23.

Builds
15.1.2507.39 · 15.2.1258.34 · 15.2.1544.11
Servicing branch
CU14
Security
1 fixed

For servers running Cumulative Update 14: 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?

What changes

Fixes 7 changes

OWA

For: Exchange Server administrators and OWA users

  • The “We can't open this document” error in OWA after installing the March 2024 security update is fixed.1

Outlook cached mode

For: Outlook users in cached mode

  • The search error in Outlook cached mode after installing the March 2024 security update is fixed.2

Exchange health probes

  • The OwaDeepTestProbe and EacBackEndLogonProbe failures after installing the March 2024 security update are fixed.3

ECP

  • The edit permissions option in ECP can be edited again.4

Outlook

For: Outlook users

  • Outlook displays the unread message icon after installing the March 2024 security update.5

My Templates

For: Outlook users of the My Templates add-in

  • The My Templates add-in works after installing the March 2024 security update.6

Download domains

For: Exchange Server administrators and users

  • Download domains work after installing the March 2024 security update.7

New features 2 changes

Elliptic Curve Cryptography certificates

  • Exchange Server 2016 and 2019 support Elliptic Curve Cryptography certificates.8

Hybrid Modern Authentication

For: Exchange Server 2019 CU14 administrators

  • Exchange Server 2019 CU14 supports Hybrid Modern Authentication for OWA and ECP.9

Technical details

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

Data sheet

Released
2024-04-23
Classification
Updates
Type
Cumulative update
Servicing branch
CU14
Replaces
KB5036386, KB5036401, KB5036402
Replaced by
KB5044062
VersionBuildChannel
2016 15.1.2507.39 General availability
2019 15.2.1258.34 General availability
2019 15.2.1544.11 General availability

Security

1 vulnerability fixed
1 important
VulnerabilitySeverityCVSS
CVE-2024-26198
Microsoft Exchange Server Remote Code Execution Vulnerability
 Important 8.8

Sources

Updated
Cited passages from Microsoft's official notes (9)
  1. 1. “We can't open this document” error in OWA after installing March 2024 SU support.microsoft.com
  2. 2. Search error in Outlook cached mode after installing March 2024 SU support.microsoft.com
  3. 3. OwaDeepTestProbe and EacBackEndLogonProbe fail after installing March 2024 SU support.microsoft.com
  4. 4. Edit permissions option in the ECP can't be edited support.microsoft.com
  5. 5. Outlook doesn't display unread message icon after installing Exchange Server March 2024 SU support.microsoft.com
  6. 6. My Templates add-in doesn't work after installing Exchange Server March 2024 SU support.microsoft.com
  7. 7. Download domains not working after installing the March 2024 SU support.microsoft.com
  8. 8. Elliptic Curve Cryptography certificates support in Exchange Server 2016 and 2019 support.microsoft.com
  9. 9. Hybrid Modern Authentication support for OWA and ECP in Exchange Server 2019 CU14 support.microsoft.com
Checked automatically: 8 of 8 checks passed, 9 quoted passages · compared with Microsoft's page on Oct 20, 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 3/5, 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