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Windows 10 1809Operating system · Microsoft

CVE-2026-42977

HIGH · 7.8 CVSS v3.1 Published 2026-06-09
Fix available
A fix is available. Upgrade to 10.0.17763.8880 / 10.0.19044.7417 or later.
See remediation →
80/100
Remediation priority · High
Zero-click

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
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Push Notifications allows an authorized attacker to elevate privileges locally.

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 race condition vulnerability exists in Windows Push Notifications where improper synchronization of shared resources allows a locally authorized attacker to exploit the timing window and elevate privileges to SYSTEM level. The vulnerability stems from concurrent access to shared state without adequate locking mechanisms in the notification subsystem.

MitigationApply the Microsoft security update for CVE-2026-42977 to patch the Windows Push Notifications component, or ensure Windows automatic updates are enabled and systems are fully patched.

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 1809Operating system
Affected:< 10.0.17763.8880
Windows 10 21h2Operating system
Affected:< 10.0.19044.7417
Windows 10 22h2Operating system
Affected:< 10.0.19045.7417
Windows 11 23h2Operating system
Affected:< 10.0.22631.7219
Windows 11 24h2Operating system
Affected:< 10.0.26100.8655
Windows 11 25h2Operating system
Affected:< 10.0.26200.8655
Windows 11 26h1Operating system
Affected:< 10.0.28000.2269
Windows Server 2019Operating system
Affected:< 10.0.17763.8880

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
High
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/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. Retrieve Windows build number
    Open Command Prompt and run `winver` or `systeminfo | findstr /B /C:"OS Version"` to display the exact Windows build version
    Affected if The displayed build number falls below the fixed versions for your specific Windows release (17763.8880, 19044.7417, 19045.7417, 22631.7219, 26100.8655, 26200.8655, or 28000.2269)
  2. Identify Windows release version
    Run `ver` or check System Properties to determine if your system is Windows 10 1809, 10 21h2, 10 22h2, Windows 11 23h2/24h2/25h2/26h1, or Windows Server 2019
    Affected if Your Windows release matches any of the affected versions listed in the CVE
  3. Confirm build number is within vulnerable range
    Compare your exact build number (for example, 10.0.19045.5000) against the threshold for your release. For Windows 10 22h2 the vulnerable range is < 10.0.19045.7417
    Affected if Your build number is lower than the fixed build for your specific Windows release and build combination

You are affected if your Windows version and build number match any of the affected ranges and your system has not yet received the corresponding security update.

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 10.0.17763.8880 / 10.0.19044.7417 / 10.0.19045.7417 or later
Fixed in 10.0.17763.888010.0.19044.741710.0.19045.7417
Interim mitigation

Apply the Microsoft security update for CVE-2026-42977 to patch the Windows Push Notifications component, or ensure Windows automatic updates are enabled and systems are fully patched.

Recommended fix High confidence

Windows 10 1809: 10.0.17763.8880 | Windows 10 21h2: 10.0.19044.7417 | Windows 10 22h2: 10.0.19045.7417 | Windows 11 23h2: 10.0.22631.7219 | Windows 11 24h2: 10.0.26100.8655 | Windows 11 25h2: 10.0.26200.8655 | Windows 11 26h1: 10.0.28000.2269 | Windows Server 2019: 10.0.17763.8880

  1. Open Windows Settings by pressing Win+I
  2. Navigate to Windows Update (Update & Security > Windows Update)
  3. Click 'Check for updates' to download and install all available security updates
  4. Restart your computer when prompted to complete the installation
  5. Alternatively, manually download the specific security update from the Microsoft Update Catalog (search for the KB number corresponding to CVE-2026-42977 for your Windows version)
  6. Verify the update was installed by checking Windows Update history or running 'winver' to confirm the build number matches the fixed version for your product
Caveat Standard Windows update risks: ensure backups of critical data before applying updates; some updates may require restart

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

Fix this in Windows 10 1809 Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,440
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,304.

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-2026-42977 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