Patch tracker / CVE reference / CVE-2026-45501

CVE-2026-45501

CVE-2026-45501 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.

Risk summary

Critical

9.6

CVSS

70%

EPSS, 30 days

Critical

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.

Senserva AI Opinion for CVE-2026-45501

CVE-2026-45501 is a spoofing flaw in on-premises Microsoft Exchange Server, hitting Subscription Edition RTM plus the current cumulative updates for the 2016 and 2019 lines (CU23 and CU15). Spoofing on Exchange typically means an attacker can forge identity or content in a way that supports phishing or authentication trickery against your mail environment. Severity is rated High with a CVSS of 8.8, though EPSS puts exploit probability at only 6 percent, and it is not in CISA KEV or tied to ransomware.

Do this: Inventory your on-prem Exchange servers and apply Microsoft's security update for the Subscription Edition, 2016 CU23, and 2019 CU15 builds you are running.

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

Senserva AI Opinion and rich prompt for CVE-2026-45501

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-2026-45501 (source: https://senserva.com/cve/CVE-2026-45501.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2026-45501: 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.

Official patch(es) for CVE-2026-45501

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-2026-45501. 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

Scope and sources

Affected products

Fixed by the same updates

CVE-2026-42897 CVE-2026-45500 CVE-2026-45502 CVE-2026-45503 CVE-2026-45504 CVE-2026-45583 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.