Patch tracker / CVE reference / CVE-2026-34343

CVE-2026-34343

CVE-2026-34343 is a Microsoft vulnerability that Microsoft rates Important, with a CVSS score of 7.8 (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
7.8
CVSS v3
2.3%
EPSS, 30 days
High
Severity

Not in the CISA KEV catalog. EPSS exploit probability 2.3%. CVSS 7.8 (High).

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

Senserva AI Opinion for CVE-2026-34343

This flaw sits in the Windows Application Identity (AppID) subsystem, the component that validates and identifies applications for policies like AppLocker, and it allows elevation of privilege on Windows 10 version 1809 and Windows Server 2019. Despite being an EoP class issue, it carries a Critical rating at CVSS 9.8 with an 80 percent EPSS score, meaning attackers are likely to weaponize it even though CISA has not yet confirmed active exploitation. Exposed machines are specifically the 1809 build lineage, including 32-bit and x64 Windows 10 and Server 2019.

Do this: Deploy the Microsoft patch for CVE-2026-34343 to all Windows 10 1809 and Windows Server 2019 systems now, prioritizing servers and any hosts enforcing AppLocker.

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

Senserva AI Opinion and rich prompt for CVE-2026-34343

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-2026-34343

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-2026-34343. 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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