Patch tracker / CVE reference / CVE-2026-40359
CVE-2026-40359
CVE-2026-40359 is a high severity Microsoft vulnerability with a CVSS score of 7.8. Microsoft has shipped the fix: deploy one of the 2 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.
High severity Microsoft vulnerability, CVSS 7.8. Fixed by 2 Microsoft security updates.
Risk summary
Updated July 25, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
Senserva AI Opinion for CVE-2026-40359
Server-side exposure sets this Microsoft Excel remote code execution flaw apart: Office Online Server is affected along with Office 2019, so a malicious workbook uploaded for browser preview could execute code on the rendering farm rather than a single desktop. Severity is High (CVSS 7.8) and EPSS sits at 0 percent, with no known exploitation, so this is important hygiene rather than a fire. It is one of a trio of Excel flaws against the same targets this cycle.
Do this: Patch Office Online Server farms behind SharePoint first, since one crafted spreadsheet there affects every user of the preview service.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2026-40359
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for CVE-2026-40359
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 <1%. CVSS 7.8 (High).
This CVE is among the lower half of tracked Microsoft CVEs by EPSS exploit probability.
Official patch(es) for CVE-2026-40359
Moderate priority: schedule it in your normal patch cycle. In Intune or Defender, confirm whether the fixing updates KB5002865, KB5002871 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-2026-40359. 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.
Affected products
Common questions about CVE-2026-40359
Is CVE-2026-40359 actively exploited?
It is not currently listed in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score puts the probability of exploitation in the next 30 days at <1%.
What patch fixes CVE-2026-40359?
Microsoft fixed CVE-2026-40359 in KB5002865, KB5002871. Download from the Microsoft Update Catalog, or let Intune, Windows Update, or WSUS deliver it.
Which products are affected by CVE-2026-40359?
Microsoft Office 2019 for 32-bit editions, Microsoft Office 2019 for 64-bit editions, Office Online Server.
Can I ask my own AI about CVE-2026-40359?
Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2026-40359's key facts: severity, CVSS, EPSS exploit probability, CISA KEV status, and the fixing KB. Copy it into Claude, ChatGPT, or Copilot for a triage plan; the data is refreshed twice a day (5 AM and 3 PM US Central).
Fixed by the same updates
If you are patching CVE-2026-40359, the same updates also fix these:
Authoritative references
Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.
