dbcve.org
Windows 10 1607Operating system · Microsoft

CVE-2026-49793

HIGH · 7.8 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 →
80/100
Remediation priority · High
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
Heap-based buffer overflow in Windows Resilient File System (ReFS) allows an authorized attacker to execute code locally.

In the news

Third-party coverage
Trending covered by 1 outlet this week · latest 1w 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 heap-based buffer overflow vulnerability exists in the Windows Resilient File System (ReFS) that allows a locally authenticated attacker to execute arbitrary code by exploiting improper bounds checking during file system operations.

MitigationApply Microsoft security updates for ReFS when available; restrict local administrative access to reduce attack surface; monitor for suspicious file system activity.

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< 10.0.28000.2525
Windows Server 2016Operating system
Affected:< 10.0.14393.9339

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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/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 ReFS file system is in use
    Open PowerShell and run 'Get-Volume | Select-Object DriveLetter, FileSystemLabel, FileSystem' to list all volumes and their file systems. Look for any volume with FileSystem equal to 'ReFS' or 'ReFSv1'
    Affected if Any volume on the system is formatted with ReFS and the Windows version falls within the affected ranges below
  2. Determine Windows version and build number
    Run 'winver' from the Run dialog or run 'systeminfo' in Command Prompt/PowerShell to obtain the exact OS version and build number (e.g., 10.0.14393.9339)
    Affected if The system is running a version lower than the corresponding threshold for its Windows release as listed in step 3
  3. Compare version against affected ranges for Windows 10 1607 and Windows Server 2016
    If the OS version begins with 10.0.14393, verify the build number is less than 9339. Run 'reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion" /v CurrentBuild' and '/v CurrentBuildNumber' to confirm
    Affected if Running Windows 10 1607 or Windows Server 2016 with build number below 10.0.14393.9339 AND ReFS is in use
  4. Compare version against affected ranges for Windows 10 1809
    If the OS version begins with 10.0.17763, verify the build number is less than 9020
    Affected if Running Windows 10 1809 with build number below 10.0.17763.9020 AND ReFS is in use
  5. Compare version against affected ranges for Windows 10 21h2 and 22h2
    If the OS version begins with 10.0.19044 or 10.0.19045, verify the build number is less than 7548
    Affected if Running Windows 10 21h2 (build < 10.0.19044.7548) or 22h2 (build < 10.0.19045.7548) AND ReFS is in use
  6. Compare version against affected ranges for Windows 11
    Identify the Windows 11 release (24h2, 25h2, or 26h1) from the OS version. Check if version < 10.0.26100.8875 for 24h2, < 10.0.26200.8875 for 25h2, or < 10.0.28000.2269/< 10.0.28000.2525 for 26h1
    Affected if Running Windows 11 24h2, 25h2, or 26h1 with build below the respective threshold AND ReFS is in use

A system is affected if it uses ReFS on any volume AND runs a Windows version within the affected ranges listed (build numbers below the specified thresholds for the corresponding Windows release).

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.

From vendor data
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 Microsoft security updates for ReFS when available; restrict local administrative access to reduce attack surface; monitor for suspicious file system activity.

Fix this in Windows 10 1607 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing8.0 h
  • Review / QA4.0 h
18.0 hours of engineering $3,080
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,928.

Scan for this in your stack

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dbcve dependency scanner

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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-2026-49793 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