Patch tracker / CVE reference / CVE-2026-40358

CVE-2026-40358

CVE-2026-40358 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 v3

<1%

EPSS, 30 days

High

Severity

Not in the CISA KEV catalog. EPSS exploit probability <1%. CVSS 8.4 (High).

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

Senserva AI Opinion for CVE-2026-40358

CVE-2026-40358 is a High severity (CVSS 8.4) remote code execution flaw in Microsoft Office 2019 and Microsoft 365 Apps for Enterprise, meaning a crafted document could run attacker code with the user's privileges. Exposure is broad because these are standard productivity apps on most Windows endpoints, but the EPSS score is 0% and it is not listed in CISA KEV or tied to ransomware yet. The gap between the high impact rating and the currently low exploitation signal is what makes this a patch-on-schedule item rather than an emergency.

Do this: Deploy the Microsoft Office 2019 and Microsoft 365 Apps for Enterprise security update to all affected 32-bit and 64-bit endpoints through your normal patch cycle.

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

Senserva AI Opinion and rich prompt for CVE-2026-40358

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-2026-40358 (source: https://senserva.com/cve/CVE-2026-40358.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2026-40358: High severity Microsoft vulnerability, CVSS 8.4
- EPSS 30-day exploitation probability: <1%
- Actively exploited (CISA KEV): no
- Fixed by: KB5002866
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 under 1%.

Fixed by KB5002866. 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-2026-40358

Moderate priority: schedule it in your normal patch cycle. In Intune or Defender, confirm whether the fixing update KB5002866 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-2026-40358. 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.

KB5002866

Scope and sources

Affected products

Fixed by the same update

CVE-2026-40363

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.