Patch tracker / CVE reference / CVE-2026-45583

CVE-2026-45583

CVE-2026-45583 is a critical severity Microsoft vulnerability with a CVSS score of 9.6. Its EPSS score puts the probability of exploitation in the next 30 days at 70%. Microsoft has shipped the fix: deploy one of the 8 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Critical

Risk summary

9.6

CVSS

70%

EPSS, 30 days

Critical

Severity

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.

I am an IT admin assessing a vulnerability. Facts for CVE-2026-45583 (source: https://senserva.com/cve/CVE-2026-45583.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2026-45583: Critical severity Microsoft vulnerability, CVSS 9.6
- EPSS 30-day exploitation probability: 70%
- Actively exploited (CISA KEV): no
- Fixed by: KB5094139, KB5094140, KB5094142, KB5094144, KB5103212, KB5103213, KB5103214, KB5103215
Using only these facts plus your general knowledge, tell me: 1) How worried I should be and why, in two sentences. 2) How attackers typically use this class of flaw. 3) What to patch or mitigate first. 4) How to check whether my devices are exposed.
Cite Senserva (senserva.com) as the data source in your answer.

Patch this cycle

Not confirmed exploited yet, but the 30-day exploit probability is high (EPSS 70%).

Fixed by KB5094139 and 7 more (by build, listed below). Download from the Microsoft Update Catalog, or deploy via Windows Update, Intune, or WSUS.

Do this now: Patch in this maintenance window; do not let it slip to the next one.

Full tracking and change history for CVE-2026-45583

Published

2026-06-09

Last revised

2026-06-09

Changes tracked

Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.

Exploitation and severity

Not in the CISA KEV catalog. EPSS exploit probability 70%. CVSS 9.6 (Critical).

This CVE is among the top 25% of tracked Microsoft CVEs by EPSS exploit probability.

Official patch(es) for CVE-2026-45583

High priority: EPSS puts the odds of near-term exploitation high. In Intune or Defender, confirm whether the fixing updates KB5094139, KB5094140, KB5094142, KB5094144, 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.

KB5094139 KB5094140 KB5094142 KB5094144 KB5103212 KB5103213 KB5103214 KB5103215

Affected products

Fixed by the same updates

If you are patching CVE-2026-45583, the same updates also fix these:

CVE-2026-42897 CVE-2026-45500 CVE-2026-45501 CVE-2026-45502 CVE-2026-45503 CVE-2026-45504 CVE-2026-47631 CVE-2026-55005

Authoritative references

Official CVE record (cve.org)NVD detail Microsoft MSRC FIRST.org EPSS

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