Skip to the content
The Update Bureau
Exchange Server 2019 CU14 Exchange Server 2019 CU14 ESU only Security update
Patch Tuesday Zero-day

KB5035606

KB5035606: Security update for Exchange Server 2019 CU14, February 2024. Mail-server access flaw is under attack

In short

Fixes one critical flaw in Exchange Server 2019 CU14. Attackers are already using it to gain higher access.

Does it affect you? Applies to: This update is for Exchange Server 2019 CU14. Only organizations in the Extended Security Update program can get it.

Build
15.2.1544.4
Servicing branch
CU14
Security
1 fixed · 1 critical · 1 exploited
Review notes Additional details from the official release notes (1) Read note
  • What to do KB5035606 is a security update for Exchange Server 2019 CU14 and is available only through the Extended Security Update program.

The official sources are linked at the end of the page.

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?

In detail

  • Security Fixes 1 critical vulnerability: CVE-2024-21410. Attackers are using it to gain higher access in Exchange Server.

Technical details

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

Data sheet

Released
2024-02-13
Classification
Security Updates
Type
Cumulative update
Servicing branch
CU14
Replaced by
KB5036401
VersionBuildChannel
2019 15.2.1544.4 General availability

Security

1 vulnerability fixed
1 exploited 1 critical
VulnerabilitySeverityCVSS
CVE-2024-21410 Exploited
Microsoft Exchange Server Elevation of Privilege Vulnerability
 Critical 9.8

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 4/5, 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