Windows Network File System Denial of Service Vulnerability

Buffer over-read in Windows Network File System allows an unauthorized attacker to deny service over a network.

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5.9CVSS out of 10High severity

Scope

What the vendor says is affected

Windows 10 Version 1809 for 32-bit Systems
Windows 10 Version 1809 for x64-based Systems
Windows Server 2019
Windows Server 2019 (Server Core installation)
Windows Server 2022
Windows Server 2022 (Server Core installation)
Windows Server 2025 (Server Core installation)
Windows Server 2025
Windows 10 Version 1607 for 32-bit Systems
Windows 10 Version 1607 for x64-based Systems
Windows Server 2016
Windows Server 2016 (Server Core installation)
Windows Server 2012
Windows Server 2012 (Server Core installation)
Windows Server 2012 R2
Windows Server 2012 R2 (Server Core installation)

Versions the vendor lists as fixed

10.0.17763.9121
10.0.20348.5499
10.0.20348.5440
10.0.26100.33296
10.0.26100.33222
10.0.14393.9418
6.2.9200.26280
6.3.9600.23338

Next step

What the vendor recommends

Install KB5120238. Install KB5120242. Install KB5120229. Install KB5120233. Install KB5120228. Install KB5120418. Install KB5120386. Install KB5120385.

Review the complete instructions on the vendor's site

Update history

What changed in later vendor updates

SecurityAlert records field-level changes from the point we begin following a bulletin. Earlier vendor changes may not have a field-by-field record.

Aug 27, 2026 at 3:05 AM UTC
- The vendor changed the advisory's last-updated date.
Aug 20, 2026 at 7:00 PM UTC
- The vendor changed its remediation guidance.

Timeline

When this advisory changed

Aug 11, 2026 at 7:00 AM UTC
Published by Microsoft Security Response Center
The publication date reported by the vendor.
Aug 20, 2026 at 6:50 PM UTC
Added to SecurityAlert
We collected the advisory from the official source.
Aug 26, 2026 at 7:00 AM UTC
Updated by Microsoft Security Response Center
The vendor changed the advisory after it was first published.
Sep 2, 2026 at 5:15 PM UTC
Confirmed at the source
Our collector saw this advisory during a later source check.

Vulnerabilities

CVEs named in this advisory

CVE-2026-68819View CVSS, KEV, EPSS, and threat context

Source

Start with the vendor's bulletin

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Vendor: Microsoft Security Response Center
Advisory ID: CVE-2026-68819
Last source check: Sep 13, 2026 at 2:40 AM UTC

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What the vendor says is affected

Versions the vendor lists as fixed

What the vendor recommends

What changed in later vendor updates

When this advisory changed

CVEs named in this advisory

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