CVE-2026-50466
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 · uneditedUse after free in Windows Brokering File System allows an authorized attacker to elevate privileges locally.
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 confidenceA use-after-free vulnerability exists in the Windows Brokering File System (BFS) that allows a locally authorized attacker to manipulate memory after it has been freed, leading to privilege escalation from their current authorization level to higher system privileges.
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< 10.0.26100.8875< 10.0.26200.8875< 10.0.28000.2269< 10.0.28000.2525< 10.0.26100.33158CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Check Windows build numberOpen Command Prompt or PowerShell and run: winver OR systeminfo | findstr /C:"Build"Affected if The build number is lower than 26100.8875 for 24h2, 26200.8875 for 25h2, 28000.2269 or 28000.2525 for 26h1, or 26100.33158 for Server 2025
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Verify Windows version nameRun winver to confirm the specific Windows 11 version (24h2, 25h2, or 26h1) or check System Properties for Windows Server 2025Affected if The installed version matches an affected version branch but the build number is below the patched threshold
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Confirm BFS component presenceCheck for the presence of the Brokering File System by examining %SystemRoot%\System32\drivers\bfs.sys file existence, or query via: reg query "HKLM\SYSTEM\CurrentControlSet\Services\BFS"Affected if The BFS driver file exists on the system (the vulnerability applies when BFS is loaded)
The system is affected if it runs any of the listed Windows versions/builds below the patched thresholds and the BFS driver is present on the system.
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.
From vendor data10.0.26100.887510.0.26100.3315810.0.26200.8875
Apply the Microsoft security update for CVE-2026-50466 when released, as this is a kernel-level file system vulnerability that requires vendor-supplied patching rather than configuration changes.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-50466 — 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-2026-50466 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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