CVE-2026-50300
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 · uneditedInteger underflow (wrap or wraparound) in Windows Kernel allows an authorized attacker to disclose information 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 confidenceAn integer underflow vulnerability exists in the Windows Kernel that allows a locally authorized attacker to exploit wraparound behavior in arithmetic operations, potentially disclosing sensitive information from kernel memory.
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< 10.0.28000.2269< 10.0.28000.2525< 10.0.14393.9339CVSS 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 checksWork through these to decide whether this CVE applies to you.
-
Retrieve Windows build versionRun 'winver' or execute 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' or check registry key 'HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\CurrentBuild'Affected if Unable to determine the build number - cannot assess exposure
-
Identify Windows product lineCheck if the system is Windows 10, Windows 11, or Windows Server 2016 by running 'winver' or reviewing the OS Name from systeminfoAffected if System is not one of the listed affected products (Windows 10 1607/1809/21h2/22h2, Windows 11 24h2/25h2/26h1, or Windows Server 2016)
-
Compare build against fixed versions for your productFor Windows 10 1607/Server 2016: ensure build >= 14393.9339. For Windows 10 1809: ensure build >= 17763.9020. For Windows 10 21h2/22h2: ensure build >= 19045.7548. For Windows 11 24h2: ensure build >= 26100.8875. For Windows 11 25h2: ensure build >= 26200.8875. For Windows 11 26h1: ensure build >= 28000.2525Affected if Installed build number is lower than the corresponding fixed build for your Windows version
-
Verify kernel-level access is not already compromisedCheck for unexpected new local users or groups with administrative rights using 'net user' and 'net localgroup administrators'; review recent security event logs for Account Management events (4720-4726)Affected if Unexpected local users or privilege escalations detected, which may indicate active exploitation of kernel flaws
The system is affected if the installed Windows build number falls below the fixed version for your specific Windows product line, as this integer underflow exists in the kernel of unpatched versions.
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 Kernel when available; prioritize patching for systems with local user access. Restrict local user privileges where possible to reduce attack surface.
Upgrade to the latest Windows cumulative update containing the fix: Windows 10 1607 -> 10.0.14393.9339 | Windows 10 1809 -> 10.0.17763.9020 | Windows 10 21h2 -> 10.0.19044.7548 | Windows 10 22h2 -> 10.0.19045.7548 | Windows 11 24h2 -> 10.0.26100.8875 | Windows 11 25h2 -> 10.0.26200.8875 | Windows 11
- Identify the current Windows version by running 'winver' or checking System Properties
- Determine which version branch your system is on (e.g., Windows 10 22h2, Windows 11 24h2)
- Open Windows Settings > Update & Security > Windows Update
- Click 'Check for updates' to download and install the latest cumulative update
- Restart the system after the update completes
- Verify the installed version matches or exceeds the fixed version for your branch using 'winver'
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation2.0 h
- Testing8.0 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 $4,928.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-50300 — 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-2026-50300 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
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.
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.
- 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