dbcve.org
Windows 10 1607Operating system · Microsoft

CVE-2026-49801

MEDIUM · 5.5 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 →
57/100
Remediation priority · Elevated
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
Use of uninitialized resource in Windows SMB allows an authorized attacker to disclose information 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

This is a local information disclosure vulnerability in Windows SMB (Server Message Block) where an uninitialized resource (likely memory) is used, allowing an authorized attacker to read sensitive information from memory contents. The attack requires local access and authentication, and does not lead to code execution.

MitigationApply the relevant Microsoft Windows security update for this CVE to all affected Windows systems. Prioritize systems with SMB exposure, and test SMB functionality after patching to ensure no service disruption.

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

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

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. Identify Windows version and build number
    Run 'winver' to get the OS version and build, or use 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"'
    Affected if The build number is lower than the affected thresholds for your Windows version (e.g., for Windows 10 22h2, build < 19045.7548) or if running Windows Server 2012/2012 R2 (all versions)
  2. Confirm SMB is enabled
    Check if the SMB service is running: run 'Get-Service -Name SMB1' or 'Get-SmbServerConfiguration' in PowerShell. Also check Windows Features for SMB1 under 'Programs and Features' > 'Turn Windows features on or off'
    Affected if SMB is enabled and the Windows version/build is in the affected range
  3. Check SMB version configuration
    Run 'Get-SmbServerConfiguration | Select-Object -Property *' to see SMB1, SMB2, and protocol versions enabled
    Affected if SMB1 or SMB2 is enabled on an affected Windows version
  4. For Windows Server 2012/2012 R2 specifically
    If the system is Windows Server 2012 or Server 2012 R2 (any build), it is affected regardless of version since all versions are listed as vulnerable
    Affected if Operating system is Windows Server 2012 or Windows Server 2012 R2

You are affected if your Windows version matches one of the listed products and is below the specified build number, or if you run Windows Server 2012/2012 R2, AND SMB is enabled on the system.

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 relevant Microsoft Windows security update for this CVE to all affected Windows systems. Prioritize systems with SMB exposure, and test SMB functionality after patching to ensure no service disruption.

Recommended fix High confidence
  1. Open Windows Settings and navigate to Update & Security > Windows Update
  2. Click 'Check for updates' to download and install the latest security updates from Microsoft
  3. Alternatively, manually download the security update from the Microsoft Update Catalog (catalog.update.microsoft.com) by searching for the CVE-2026-49801 security update for your specific Windows version
  4. Restart the system after installing the updates to ensure the SMB vulnerability is patched
  5. Verify the update was installed by checking Windows Update history for the security patch date

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

Fix this in Windows 10 1607 Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-49801 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

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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-2026-49801 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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