dbcve.org
Windows 10 21h2Operating system · Microsoft

CVE-2026-45487

HIGH · 7.0 CVSS v3.1 Published 2026-06-09
Fix available
A fix is available. Upgrade to 10.0.19044.7417 / 10.0.19045.7417 or later.
See remediation →
72/100
Remediation priority · Elevated
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
Time-of-check time-of-use (TOCTOU) race condition in Program Compatibility Assistant Service 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 time-of-check time-of-use (TOCTOU) race condition exists in the Windows Program Compatibility Assistant Service. An authorized local attacker can exploit the timing window between when the service checks a resource authorization and when it uses that resource to elevate privileges to a higher level than granted.

MitigationApply the Microsoft security update for CVE-2026-45487 when released. Monitor for补丁 availability through Windows Update or Microsoft Security Response Center.

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 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 2022Operating system
Affected:< 10.0.20348.5256
Windows Server 2025Operating system
Affected:< 10.0.26100.32995

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
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify Windows build version
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Version"' to obtain the full build number (e.g., 10.0.19045.7417)
    Affected if The build number falls below the minimum fixed version for your Windows release as listed in the affected versions
  2. Confirm Windows release
    Run 'winver' to determine if the system is Windows 10 21h2, 10 22h2, Windows 11 23h2/24h2/25h2/26h1, Server 2022, or Server 2025
    Affected if The system matches any of the affected product lines and the build version is below the corresponding threshold
  3. Locate Program Compatibility Assistant Service
    Run 'Get-Service -Name "PcaSvc"' or 'sc query PcaSvc' to check if the Program Compatibility Assistant service exists
    Affected if The service is present on the system (this is a standard Windows service, so presence alone does not indicate vulnerability but is required for the flaw)
  4. Check service status
    Run 'sc queryex PcaSvc' or inspect the service via Services.msc to determine if it is running
    Affected if The service is running (the race condition can only be exploited when the service is active)

A user is affected if their Windows build version is below the fixed threshold for their specific Windows release AND the Program Compatibility Assistant service is installed and running 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 10.0.19044.7417 / 10.0.19045.7417 / 10.0.20348.5256 or later
Fixed in 10.0.19044.741710.0.19045.741710.0.20348.5256
Interim mitigation

Apply the Microsoft security update for CVE-2026-45487 when released. Monitor for补丁 availability through Windows Update or Microsoft Security Response Center.

Recommended fix High confidence

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 2022: 10.0.20348.5256 | Windows Server 2025: 10.0.26100.32995

  1. 1. Identify the current Windows version and build by running 'winver' or 'systeminfo' in Command Prompt
  2. 2. Determine which build version is required for your Windows edition from the affected versions list
  3. 3. Open Windows Settings > Update & Security > Windows Update
  4. 4. Click 'Check for updates' to download and install the latest security updates
  5. 5. Alternatively, manually download the specific security update from the Microsoft Update Catalog for your Windows version (KB reference available at msrc.microsoft.com)
  6. 6. After installation, restart the system to apply the update
  7. 7. Verify the fix by checking the installed build version matches or exceeds the fixed version for your Windows edition
Caveat Standard Windows security update; no expected breaking changes for typical workloads

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

Fix this in Windows 10 21h2 Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.

Scan for this in your stack

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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-2026-45487 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