Patch tracker / KB5066368

KB5066368: Microsoft Exchange Server Subscription Security Update (October 2025)

KB5066368 is a High security update for Microsoft Exchange Server Subscription, released 2025-10-14. It closes 3 CVEs with a maximum CVSS of 8.8. It is the 19th largest of the 60 updates Microsoft shipped that month, by CVEs closed.

Update summary

High
2025-10-14
Released
3
CVEs fixed
8.8
Max CVSS v3
High
Severity
Deploy this cycle
Fixes 3 CVEs for Microsoft Exchange Server Subscription. No confirmed in-the-wild exploitation in this set today.

Fixes 3 CVEs. Most severe CVSS 8.8 (High). EPSS exploit probability up to <1%. Among the lower half of tracked Microsoft updates by EPSS exploit probability.

Senserva found thiswe track every release for this product line, so we can tell you this package is behind

A newer security update for Microsoft Exchange Server 2019 Cumulative Update 15 has shipped since this one: KB5121573 (2026-08-11). For cumulative update families the newer package includes these fixes, so installing that one is usually the shorter path. Verify against your own update rings before you skip this package.

Microsoft Update Catalog: download KB5066368Microsoft support article
Senserva AI Opinion for KB5066368

KB5066368 patches three CVEs in on-premises Exchange Server, spanning 2019 Cumulative Updates 14 and 15 plus the new Subscription Edition RTM, with a highest Severity of High at CVSS 8.8. Organizations still running Exchange on-premises are exposed, and the inclusion of the Subscription Edition build signals this is the current supported servicing baseline. None of the three CVEs are on the CISA KEV list or ransomware-linked, and EPSS remains at 1 percent, so exploitation pressure is low for now.

Do this: Confirm your Exchange servers are on CU14, CU15, or Subscription Edition RTM and deploy KB5066368 during your next maintenance window.

AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for KB5066368

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

Full tracking and change history for KB5066368

Released
2025-10-14
Last changed
2025-10-14
Changes tracked
1

Senserva began recording day-to-day change history on 2026-07-07, and refreshes it several times a day. Release dates are historical where Microsoft publishes them; revision history is tracked from that date forward, so it does not include changes made before then.

Check if KB5066368 is installed

Elevated PowerShell. No output means it is not installed.

CVEs fixed by this update

Sorted exploited-first, then by CVSS. Every CVE links to its Senserva page with the full risk facts, references, and a ready-to-paste AI prompt.

CVESeverityCVSSEPSSExploited
CVE-2025-59249High8.8<1%No
CVE-2025-53782High8.4<1%No
CVE-2025-59248High7.5<1%No

Scope and sources

Affected products
Also released in October 2025

KB5070879

1 CVE · Critical · exploited

KB5070881

1 CVE · Critical · exploited

KB5070882

1 CVE · Critical · exploited

KB5070883

1 CVE · Critical · exploited

KB5070884

1 CVE · Critical · exploited

KB5070886

1 CVE · Critical · exploited

KB5070887

1 CVE · Critical · exploited

KB5070892

1 CVE · Critical · exploited

The full month, summarized: Microsoft Patch Tuesday.

Authoritative references
Official KB5066368 page (Microsoft Support)Microsoft Update CatalogMicrosoft Security Update Guide

See this and every Microsoft update ranked by real-world risk on the Microsoft Patch Tracker.

New to a term on this page? CVE, KB, KEV, CVSS, and EPSS are each explained once, on the Senserva security lexicon. Reference: Microsoft CVE and vulnerability management and the Microsoft patching guide.
Provided as is, without warranty; verify against the vendor advisory before acting. Data notice and terms.