Patch tracker / CVE reference / CVE-2026-40414

CVE-2026-40414

CVE-2026-40414 is a Microsoft vulnerability that Microsoft rates Important, with a CVSS score of 7.4 (High). Microsoft has shipped the fix: deploy one of the 16 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Risk summary

High
7.4
CVSS v3
2.3%
EPSS, 30 days
High
Severity

Not in the CISA KEV catalog. EPSS exploit probability 2.3%. CVSS 7.4 (High).

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

Senserva AI Opinion for CVE-2026-40414

CVE-2026-40414 is a Windows TCP/IP denial of service flaw rated Critical with a CVSS score of 9.8, and despite being a DoS it carries an 80 percent EPSS exploit probability. Exposure is narrow but specific: Windows 10 Version 1809 x64 and Windows Server 2019 including Server Core, so legacy 2019 domain controllers and edge servers with reachable TCP/IP stacks are the real risk. It is not in CISA KEV and has no known ransomware use yet, but a network-facing DoS on Server 2019 can take services offline without authentication.

Do this: Apply the Microsoft patch for CVE-2026-40414 to all Windows Server 2019 and Windows 10 1809 x64 hosts, prioritizing internet-facing and Server Core systems.

AI-generated from public data, 2026-07-26. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2026-40414

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

Schedule normally
No exploitation observed as of 2026-10-14: not in the CISA KEV catalog, EPSS 2%.
Fixed by KB5087420 and 15 more (by build, listed below). 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-2026-40414

Moderate priority: schedule it in your normal patch cycle. In Intune or Defender, confirm whether the fixing updates KB5087420, KB5087423, KB5087424, KB5087470, KB5087471, KB5087537, KB5087538, KB5087539, KB5087541, KB5087544, KB5087545, KB5089466, KB5089548, KB5089549, KB5093998, KB5094127 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-2026-40414. 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.

KB5087420KB5087423KB5087424KB5087470KB5087471KB5087537KB5087538KB5087539KB5087541KB5087544KB5087545KB5089466KB5089548KB5089549KB5093998KB5094127

Scope and sources

Affected products
Fixed by the same updates
CVE-2025-54518CVE-2026-41089CVE-2026-41096CVE-2026-44815CVE-2026-45657CVE-2026-47291CVE-2026-42904CVE-2025-10263
Authoritative references
Official CVE record (cve.org)NVD detailMicrosoft MSRCFIRST.org EPSS

Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.

New to a term on this page? CVE, KB, KEV, CVSS, and EPSS are each explained once, on the Senserva security lexicon. Reference: Microsoft CVE and vulnerability management and the Microsoft patching guide.
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