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-2026-45583

CVE-2026-45583

CVE-2026-45583 is a Microsoft vulnerability that Microsoft rates Important, with a CVSS score of 7.5 (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
7.5
CVSS v3
2.5%
EPSS, 30 days
High
Severity

Not in the CISA KEV catalog. EPSS exploit probability 2.5%. CVSS 7.5 (High).

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

Senserva AI Opinion for CVE-2026-45583

CVE-2026-45583 is a remote code execution flaw in on premises Microsoft Exchange Server, hitting the current supported builds 2016 CU23 and 2019 CU14 and CU15. Exchange servers are internet facing mail hubs holding domain credentials, so an RCE here at CVSS 8.8 is a direct path to mailbox and Active Directory compromise. It is not yet in CISA KEV and EPSS sits at 6 percent, but Exchange RCE bugs have a track record of fast weaponization once patches are reverse engineered.

Do this: Apply the Microsoft security update for your specific Exchange build (2016 CU23 or 2019 CU14/CU15) now and confirm the CU baseline is current before patching.

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

Senserva AI Opinion and rich prompt for CVE-2026-45583

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

Official patch(es) for CVE-2026-45583

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-2026-45583. 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-2026-55006
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.
All information provided as is, without warranty; verify against the vendor advisory before acting. All information and usage is subject to the Senserva EULA. Data notice and terms.