dbcve.org
Windows 10 1607Operating system · Microsoft

CVE-2026-56648

HIGH · 7.5 CVSS v3.1 Published 2026-07-14
Fix available
A fix is available. Upgrade to 10.0.14393.9339 / 10.0.17763.9020 or later.
See remediation →
81/100
Remediation priority · High
Remotely reachable Zero-click 5 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Time-of-check time-of-use (toctou) race condition in Windows Network File System allows an authorized attacker to elevate privileges over a network.

In the news

Third-party coverage
Trending covered by 1 outlet this week · latest 1mo ago

Surfaced from public web coverage — external links open in a new tab.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A time-of-check time-of-use (TOCTOU) race condition vulnerability exists in Windows Network File System (NFS). An authorized attacker who can send network requests to the NFS service can exploit the race window between checking a security-relevant condition and using the result of that check to elevate privileges to a higher level.

MitigationApply the applicable Microsoft security patch for this vulnerability when released. Until then, restrict network access to NFS services to trusted users and monitor for suspicious privilege escalation attempts.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Windows 10 1607Operating system
Affected:< 10.0.14393.9339
Windows 10 1809Operating system
Affected:< 10.0.17763.9020
Windows 10 21h2Operating system
Affected:< 10.0.19044.7548
Windows 10 22h2Operating system
Affected:< 10.0.19045.7548
Windows 11 24h2Operating system
Affected:< 10.0.26100.8875
Windows 11 25h2Operating system
Affected:< 10.0.26200.8875
Windows 11 26h1Operating system
Affected:< 10.0.28000.2269
Windows Server 2012Operating system
Affected:all versions= r2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify NFS service is installed and running
    Open Services console (services.msc) and look for 'Server for NFS' or 'NFS Service' status, or run 'Get-Service -Name *NFS*' in PowerShell
    Affected if NFS service is installed and running - the vulnerability only applies when the NFS service is accessible
  2. Check Windows version against affected ranges
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' and compare the build number to the affected version ranges
    Affected if Build number is less than the specified threshold for your Windows version (e.g., < 10.0.14393.9339 for Windows 10 1607, < 10.0.17763.9020 for Windows 10 1809, etc.)
  3. Verify NFS is exposed to network
    Check NFS server configuration in Windows Features (enable Windows Features for NFS) or via Registry: HKLM\SOFTWARE\Microsoft\ForGames\Config, or check if NFS ports (2049/TCP and 2049/UDP) are listening with 'netstat -an | findstr 2049'
    Affected if NFS ports are listening and accessible from the network - the attacker needs to send network requests to the NFS service to exploit the race condition

You are affected if the NFS service is running, your Windows build is below the version threshold, and NFS is network-accessible to an attacker.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 10.0.14393.9339 / 10.0.17763.9020 / 10.0.19044.7548 or later
Fixed in 10.0.14393.933910.0.17763.902010.0.19044.7548
Interim mitigation

Apply the applicable Microsoft security patch for this vulnerability when released. Until then, restrict network access to NFS services to trusted users and monitor for suspicious privilege escalation attempts.

Recommended fix High confidence

Windows 10/11: Latest cumulative update (minimum versions listed above). Windows Server 2012/R2: Upgrade to Windows Server 2019/2022/2025 (no patch available for EOL product)

  1. Open Settings > Update & Security > Windows Update (or Server Manager > Local Server for Windows Server)
  2. Check for updates and install the latest Windows cumulative/security update
  3. Verify the installed version matches or exceeds: 10.0.14393.9339 (Win10 1607), 10.0.17763.9020 (Win10 1809), 10.0.19044.7548 (Win10 21h2), 10.0.19045.7548 (Win10 22h2), 10.0.26100.8875 (Win11 24h2), 10.0.26200.8875 (Win11 25h2), or 10.0.28000.2269 (Win11 26h1)
  4. Restart the system when prompted
Caveat Windows Server 2012/R2 has reached end of support; upgrade required. Test updates in staging environment before production deployment.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Windows 10 1607 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,760
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-56648 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data