Patch tracker / CVE reference / CVE-2026-26109
CVE-2026-26109
CVE-2026-26109 is a high severity Microsoft vulnerability with a CVSS score of 8.4. 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.
Risk summary
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.
Office Online Server heads the affected list for this Excel remote code execution flaw, and that flips the risk model: OOS renders spreadsheets server side for browser users, so one malicious workbook can detonate on shared infrastructure instead of a single desktop. Desktop Office 2019 is affected as well. EPSS sits at 0 percent.
Do this: Patch Office Online Server farms first, then desktop Excel through normal channels.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2026-26109
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Official patch(es) for CVE-2026-26109
Moderate priority: schedule it in your normal patch cycle. In Intune or Defender, confirm whether the fixing updates KB5002846, KB5002849 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-2026-26109. 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.
Scope and sources
- Affected products
- Fixed by the same updates
- Authoritative references
Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.