dbcve.org
Windows 10 1507Operating system · Microsoft

CVE-2025-27473

HIGH · 7.5 CVSS v3.1 Published 2025-04-08
Fix available
A fix is available. Upgrade to 10.0.10240.20978 / 10.0.14393.7969 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges 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
Uncontrolled resource consumption in Windows HTTP.sys allows an unauthorized attacker to deny service over a network.

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 denial of service vulnerability exists in Windows HTTP.sys (HTTP Protocol Stack) where an unauthenticated remote attacker can cause uncontrolled resource consumption, leading to service unavailability. The vulnerability stems from insufficient bounds checking or resource limits in the HTTP protocol handler, allowing malicious network requests to exhaust memory, CPU, or connection resources.

MitigationApply the Microsoft security update for CVE-2025-27473 via Windows Update or Microsoft Update Catalog. In enterprise environments, test HTTP-based applications after patching to ensure compatibility.

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 1507Operating system
Affected:< 10.0.10240.20978
Windows 10 1607Operating system
Affected:< 10.0.14393.7969
Windows 10 1809Operating system
Affected:< 10.0.17763.7136
Windows 10 21h2Operating system
Affected:< 10.0.19044.5737
Windows 10 22h2Operating system
Affected:< 10.0.19045.5737
Windows 11 22h2Operating system
Affected:< 10.0.22621.5189
Windows 11 23h2Operating system
Affected:< 10.0.22631.5189
Windows 11 24h2Operating system
Affected:< 10.0.26100.3775

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. Check Windows version
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to identify your Windows version and build number
    Affected if The build number is lower than any of these thresholds: 10240.20978 (Win10 1507), 14393.7969 (Win10 1607), 17763.7136 (Win10 1809), 19044.5737 (Win10 21h2), 19045.5737 (Win10 22h2), 22621.5189 (Win11 22h2), 22631.5189 (Win11 23h2), 26100.3775 (Win11 24h2)
  2. Verify HTTP.sys driver status
    Run 'sc query http' in Command Prompt to check if the HTTP service is running
    Affected if The service state shows as RUNNING, indicating HTTP.sys is active and processing HTTP requests
  3. Confirm HTTP listening endpoints
    Run 'netsh http show servicestate' to list all HTTP endpoints and registered URLs
    Affected if Any HTTP or HTTPS listeners are registered, exposing the service to network requests
  4. Check for exposed network listeners
    Run 'netstat -ano | findstr ":80 "' or 'netstat -ano | findstr ":443 "' to see if ports 80 or 443 are bound to listening processes
    Affected if Ports 80 or 443 are in LISTENING state, meaning the HTTP protocol stack is accepting remote connections

You are affected if your Windows build number falls below the thresholds AND HTTP.sys is actively listening for HTTP connections on the network.

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 10.0.10240.20978 / 10.0.14393.7969 / 10.0.17763.7136 or later
Fixed in 10.0.10240.2097810.0.14393.796910.0.17763.7136
Interim mitigation

Apply the Microsoft security update for CVE-2025-27473 via Windows Update or Microsoft Update Catalog. In enterprise environments, test HTTP-based applications after patching to ensure compatibility.

Recommended fix High confidence

Install the appropriate Windows cumulative update: Windows 10 1507 to build 10.0.10240.20978 | Windows 10 1607 to build 10.0.14393.7969 | Windows 10 1809 to build 10.0.17763.7136 | Windows 10 21h2 to build 10.0.19044.5737 | Windows 10 22h2 to build 10.0.19045.5737 | Windows 11 22h2 to build 10.0.226

  1. 1. Identify the Windows version and build number by running 'winver' or 'systeminfo' in Command Prompt
  2. 2. Navigate to Windows Update by opening Settings > Update & Security > Windows Update
  3. 3. Check for available updates and install all cumulative updates
  4. 4. Alternatively, download and install the specific monthly cumulative update for your Windows version from the Microsoft Update Catalog (catalog.update.microsoft.com)
  5. 5. After installation, restart the system to apply the update
  6. 6. Verify the build number has been updated to the fixed version or higher using 'winver'
Caveat Standard Windows cumulative update apply with no special requirements; may require restart

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

Fix this in Windows 10 1507 Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,680
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,288.

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-2025-27473 in production — separate from our analysis above.

No notes yet

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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