CVE-2026-58531
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 · uneditedConcurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB allows an authorized attacker to elevate privileges over a network.
In the news
Third-party coverage- Microsoft July 2026 Patch Tuesday fixes massive 570 flaws, 3 zero-days
- Microsoft CVE Summary - Bleeping Computer
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 confidenceThis is a race condition vulnerability in Windows SMB (Server Message Block) where concurrent execution with improper synchronization on a shared resource allows an authenticated attacker to elevate privileges over a network connection.
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< 10.0.14393.9339< 10.0.17763.9020< 10.0.19044.7548< 10.0.19045.7548< 10.0.26100.8875< 10.0.26200.8875< 10.0.28000.2525all versions= r2CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Determine Windows version build numberOpen Command Prompt and run `winver` or `systeminfo | findstr /B /C:"OS Name" /C:"OS Version"` to retrieve the installed Windows build numberAffected if The build number falls below the safe thresholds (below 14393.9339 for 1607, 17763.9020 for 1809, 19044.7548 for 21h2, 19045.7548 for 22h2, 26100.8875 for 11 24h2, 26200.8875 for 11 25h2, or 28000.2525 for 11 26h1)
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Confirm SMB is enabledCheck SMB status by running `Get-SmbServerConfiguration` in PowerShell or reviewing Services for "Server" service (LanmanServer) and "SMB 1.0/CIFS File Sharing Support" in Windows FeaturesAffected if SMB server or SMB client features are installed and enabled on the system
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Verify SMB configuration exposureRun `Get-SmbServerConfiguration | Select-Object -Property EnableSMB1Protocol,EncryptData` in PowerShell to see SMB settings, and check network listeners on ports 445 and 139 with `netstat -an | findstr "445\|139"`Affected if SMB is listening on network interfaces (especially exposed to untrusted networks) or SMB1 is enabled
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Check for pending security updatesRun `Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 10` in PowerShell to list recent installed updates, or check Windows Update history for SMB-related security patchesAffected if No recent security updates addressing SMB vulnerabilities have been installed, or the system has not been patched to the fixed build numbers
A system is affected if it runs a vulnerable Windows version (matching the affected build ranges) AND has SMB enabled and exposed, with no corresponding security patches applied.
Generated from the published advisory. Verify against your own configuration.
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 · scoped10.0.14393.933910.0.17763.902010.0.19044.7548
Apply Microsoft security updates for Windows SMB when released; as compensating controls, implement network segmentation to limit SMB exposure and enforce least privilege access principles to reduce attack surface.
Windows 10 1607 to version 10.0.14393.9339 or later; Windows 10 1809 to version 10.0.17763.9020 or later; Windows 10 21h2 to version 10.0.19044.7548 or later; Windows 10 22h2 to version 10.0.19045.7548 or later; Windows 11 24h2 to version 10.0.26100.8875 or later; Windows 11 25h2 to version 10.0.262
- Identify the current Windows version by running 'winver' or 'systeminfo' in Command Prompt
- Determine which version bracket your system falls into (1607, 1809, 21h2, 22h2, 24h2, 25h2, 26h1, or Windows Server 2012 R2)
- Open Windows Update by typing 'Check for updates' in the Start menu search
- Install all available security updates, which should include the CVE-2026-58531 fix
- Alternatively, manually download the specific security update from the Microsoft Update Catalog by searching for the CVE number
- For Windows Server 2012 R2 systems: migrate to a supported Windows Server version (2016, 2019, 2022, or 2025) as no patch is available
- After patching, verify the fix by checking the installed Windows version matches or exceeds: 10.0.14393.9339 (1607), 10.0.17763.9020 (1809), 10.0.19044.7548 (21h2), 10.0.19045.7548 (22h2), 10.0.26100.8875 (24h2), 10.0.26200.8875 (25h2), or 10.0.28000.2525 (26h1)
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation8.0 h
- Implementation4.0 h
- Testing12.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-58531 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-58531 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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