Patch tracker / CVE reference / CVE-2026-34346
CVE-2026-34346
CVE-2026-34346 is a critical severity Microsoft vulnerability with a CVSS score of 9.9. Microsoft has shipped the fix: deploy one of the 10 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.
Critical severity Microsoft vulnerability, CVSS 9.9. Fixed by 10 Microsoft security updates.
Risk summary
Updated July 23, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
Senserva AI Opinion for CVE-2026-34346
CVE-2026-34346 is an information disclosure flaw in the Ancillary Function Driver for WinSock (afd.sys), the kernel driver that backs Windows socket operations, affecting Windows 10 Version 1809 and Windows Server 2019. The CVSS 5.5 Medium score and the driver involved point to local information leakage rather than remote exploitation, meaning an attacker would need existing code execution on the box first. It is not on the CISA KEV list and has no known ransomware association, so this is patch-on-schedule rather than drop-everything.
Do this: Deploy the current cumulative update for Windows 10 1809 and Server 2019 to systems still on that build, prioritizing multi-user or shared machines where a local attacker could benefit from leaked kernel memory.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2026-34346
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for CVE-2026-34346
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 7.5%. CVSS 9.9 (Critical).
This CVE is among the lower half of tracked Microsoft CVEs by EPSS exploit probability.
Official patch(es) for CVE-2026-34346
Elevated priority: high severity or a meaningful exploitation probability, sooner if an affected product is internet-facing. In Intune or Defender, confirm whether the fixing updates KB5099414, KB5099444, KB5099445, KB5099535, KB5099536, KB5099538, KB5099539, KB5099540, KB5101649, KB5101650 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-2026-34346. 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-2026-34346
Is CVE-2026-34346 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 7.5%.
What patch fixes CVE-2026-34346?
Microsoft fixed CVE-2026-34346 in KB5099414, KB5099444, KB5099445, KB5099535, KB5099536, KB5099538, KB5099539, KB5099540, KB5101649, KB5101650. Download from the Microsoft Update Catalog, or let Intune, Windows Update, or WSUS deliver it.
Which products are affected by CVE-2026-34346?
Windows 10 Version 1809 for 32-bit Systems, Windows 10 Version 1809 for x64-based Systems, Windows Server 2019.
Can I ask my own AI about CVE-2026-34346?
Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2026-34346'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 three times a day (5 AM, 12:30 PM, and 7 PM US Central).
Fixed by the same updates
If you are patching CVE-2026-34346, 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.
