Patch tracker / CVE reference / CVE-2026-40364

CVE-2026-40364

CVE-2026-40364 is a high severity Microsoft vulnerability with a CVSS score of 8.4. Microsoft has shipped the fix: deploy the update below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Risk summary

High

8.4

CVSS

4.4%

EPSS, 30 days

High

Severity

Not in the CISA KEV catalog. EPSS exploit probability 4.4%. CVSS 8.4 (High).

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

Senserva AI Opinion for CVE-2026-40364

CVE-2026-40364 is a High severity (CVSS 8.4) remote code execution flaw in Microsoft Word affecting Office 2019 (32-bit and 64-bit) and Microsoft 365 Apps for Enterprise on 32-bit systems. Word RCE typically triggers through a crafted document opened by a user, so anyone who handles inbound Office files is exposed. It is not in CISA KEV and EPSS sits at 4 percent, so there is no confirmed exploitation yet, but the low bar of a malicious document keeps this relevant.

Do this: Deploy the Microsoft update for Office 2019 and Microsoft 365 Apps across affected endpoints, prioritizing users who open documents from external email..for for Word for these builds now, prioritizing users who open external documents.

AI-generated from public data, 2026-07-23. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2026-40364

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-2026-40364 (source: https://senserva.com/cve/CVE-2026-40364.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2026-40364: High severity Microsoft vulnerability, CVSS 8.4
- EPSS 30-day exploitation probability: 4.4%
- Actively exploited (CISA KEV): no
- Fixed by: KB5002858
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.

Schedule normally

No exploitation observed: not in the CISA KEV catalog, EPSS 4%.

Fixed by KB5002858. 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.

Official patch(es) for CVE-2026-40364

Moderate priority: schedule it in your normal patch cycle. In Intune or Defender, confirm whether the fixing update KB5002858 are installed across the affected products. Senserva does this automatically across your tenant and flags every missing patch.

Apply the Microsoft security update below to fix CVE-2026-40364. 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.

KB5002858

Scope and sources

Affected products

Fixed by the same update

CVE-2026-40367 CVE-2026-35440 CVE-2026-40361 CVE-2026-40366 CVE-2026-40421

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.