Schedule normally
No exploitation observed as of 2026-09-29: not in the CISA KEV catalog, EPSS 3%.
Fixed by KB5103212 and 3 more (by build, listed below). Download from the Microsoft Update Catalog, or deploy via Windows Update, Intune, or WSUS.
Do this now: Deploy with your normal update cycle. This page refreshes daily; the verdict changes the day the data does.

Patch tracker / CVE reference / CVE-2026-55006

CVE-2026-55006

CVE-2026-55006 is a Microsoft vulnerability that Microsoft rates Important, with a CVSS score of 7.8 (High). Microsoft has shipped the fix: deploy one of the 4 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Risk summary

High
7.8
CVSS v3
2.5%
EPSS, 30 days
High
Severity

Not in the CISA KEV catalog. EPSS exploit probability 2.5%. CVSS 7.8 (High).

This CVE is among the lower half of tracked Microsoft CVEs by EPSS exploit probability.

Senserva AI Opinion for CVE-2026-55006

This is a privilege escalation flaw in on-premises Exchange Server, hitting the 2016 CU23 and 2019 CU14 and CU15 builds that most organizations still run for hybrid or legacy mailbox hosting. Exchange privilege escalation is high value because a foothold here can extend to Active Directory given how Exchange integrates with the directory, and it carries a Severity of High with a CVSS score of 7.8. It is not in the CISA KEV catalog and has no known ransomware use yet, but Exchange bugs are attacked quickly once patches are public.

Do this: Identify all Exchange 2016 CU23 and Exchange 2019 CU14 or CU15 servers and apply the Microsoft security update for CVE-2026-55006 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 CVE-2026-55006

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

Official patch(es) for CVE-2026-55006

Moderate priority: schedule it in your normal patch cycle. In Intune or Defender, confirm whether the fixing updates KB5103212, KB5103213, KB5103214, KB5103215 are installed across the affected products. Senserva does this automatically across your tenant and flags every missing patch.

Apply the Microsoft security updates below to fix CVE-2026-55006. Each KB page carries the Microsoft Update Catalog download, Microsoft's known issues for the update, a copy-paste PowerShell check for whether it is installed, and the Senserva AI read.

KB5103212KB5103213KB5103214KB5103215

Scope and sources

Affected products
Fixed by the same updates
CVE-2026-45500CVE-2026-45502CVE-2026-55008CVE-2026-45504CVE-2026-55005CVE-2026-45503CVE-2026-47631CVE-2026-55009
Authoritative references
Official CVE record (cve.org)NVD detailMicrosoft MSRCFIRST.org EPSS

Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See 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.
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