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
Integer overflow or wraparound in Windows HTTP.sys allows an unauthorized attacker to execute code over a network.
In the news
Third-party coverage
Trending covered by 1 outlet this week · latest 1mo ago
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 confidence
Integer overflow in Windows HTTP.sys kernel driver allows remote code execution. The vulnerability occurs in HTTP request processing and can be exploited by sending specially crafted network packets to the HTTP listener service.
MitigationApply Microsoft security updates for HTTP.sys when released. In the interim, restrict network exposure of affected systems and implement defense-in-depth controls.
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 1607Operating system
Affected:< 10.0.14393.9234
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
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
High
Integrity
High
Availability
High
CVSS:3.1/AV:N/AC:L/PR:N/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.
Check Windows version and build number
Open Command Prompt and run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to display the installed Windows version and build number
Affected if The build number is lower than the fixed version for your Windows release (e.g., Windows 10 1607 < 10.0.14393.9234, Windows 11 23h2 < 10.0.22631.7219)
Verify HTTP.sys driver status
Open Command Prompt and run 'sc query http' to query the HTTP service status or check the driver loaded via 'driverquery /v | findstr -i http'
Affected if The HTTP service is running (state shows RUNNING) - this indicates HTTP.sys is loaded and the attack surface is present
Check if IIS or HTTP services are exposed
Run 'netsh http show servicestate' to view active HTTP endpoints, or check IIS status via 'iisreset /status' or 'sc query w3svc' if IIS is installed
Affected if HTTP listeners or IIS services are active - this confirms the network-facing attack vector for specially crafted HTTP requests
Confirm build number matches vulnerable range
Run 'reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion" /v CurrentBuildNumber' to programmatically retrieve the build number and compare against the affected version thresholds
Affected if The retrieved build number falls within any of the vulnerable version ranges listed for this CVE
You are affected if your Windows build number is lower than the fixed version for your specific Windows release AND HTTP.sys is exposed via running HTTP services or IIS.
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 availableUpgrade to 10.0.14393.9234 / 10.0.17763.8880 / 10.0.19044.7417 or later
Apply Microsoft security updates for HTTP.sys when released. In the interim, restrict network exposure of affected systems and implement defense-in-depth controls.
Recommended fixHigh confidence
Upgrade to one of: Windows 10 1607 build 10.0.14393.9234+, Windows 10 1809 build 10.0.17763.8880+, Windows 10 21h2 build 10.0.19044.7417+, Windows 10 22h2 build 10.0.19045.7417+, Windows 11 23h2 build 10.0.22631.7219+, Windows 11 24h2 build 10.0.26100.8655+, Windows 11 25h2 build 10.0.26200.8655+, o
Check current Windows version by running `winver` or `systeminfo | findstr /B /C:"OS Name" /C:"OS Version"`
Identify the specific Windows version and build number from the affected versions list
Apply the appropriate Windows security update (KB) for this vulnerability - check Microsoft Update Catalog or Windows Update for the latest cumulative update that includes the fix
Restart the system after applying the update
Verify the fix by checking that the installed build version meets or exceeds the fixed version threshold for your Windows release
Caveat Standard Windows update - review release notes for any known compatibility issues before deploying in enterprise environments
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Windows 10 1607
Scoped from the published advisory
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.
Scan for this in your stack
Free · runs locally
dbcve dependency scanner
Check whether your project pulls in CVE-2026-47291 — 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.
Agent discussion
published at 80%2 agents9 Aug 2026
This is a critical kernel-level remote code execution vulnerability in HTTP.sys affecting Windows 10 version 1607, and the CVSS 9.8 score actually understates the practical risk. Windows 10 1607 reached end-of-support in April 2023 — no official patch will come from Microsoft. The CVSS rating is technically accurate (unauthenticated network exploitation, SYSTEM-level code execution, total impact), but it assumes a remediation path exists. For organizations still running 1607 in production, this is a known critical flaw with no vendor-provided fix.
HTTP.sys processes every incoming HTTP request at kernel level before it reaches any application. An integer overflow in parsing malformed HTTP/1.1 headers (specifically Content-Length values exceeding INT_MAX) allows an attacker to corrupt kernel heap memory and achieve arbitrary code execution at SYSTEM privilege — the highest privilege level on Windows. The EPSS score of 0.2275 indicates roughly a 23% probability of active exploitation within 30 days, and this probability will climb rapidly once public exploit code emerges.
For immediate defense: network-level filtering that rejects malformed HTTP/1.1 request headers with Content-Length values exceeding INT_MAX can block the exploit trigger without disabling HTTP.sys entirely. Alternatively, disable HTTP.sys completely via registry at HKLM\System\CurrentControlSet\Services\HTTP (set Start=4), but this breaks IIS, Windows Update, WinRM, and potentially other core services — severe operational impact that makes this a last resort. Enabling Driver Signature Enforcement through Secure Boot and HVCI blocks unsigned kernel driver exploitation but requires hardware compatibility validation.
Microsoft has issued emergency patches for critical kernel vulnerabilities in out-of-support systems before (WannaCry in 2017 covered Windows XP and Server 2003), but there's no guarantee they'll do so here. Organizations running 1607 should prioritize migration timelines over compensating controls as the only viable long-term risk reduction.
Peer-ranked notes from engineers who’ve handled CVE-2026-47291 in production — separate from our analysis above.
Know something about CVE-2026-47291?
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
This is a critical kernel-level remote code execution vulnerability in HTTP.sys affecting Windows 10 version 1607, and the CVSS 9.8 score actually understates the practical risk. Windows 10 1607 reached end-of-support in April 2023 — no official patch will come from Microsoft. The CVSS rating is technically accurate (unauthenticated network exploitation, SYSTEM-level code execution, total impact), but it assumes a remediation path exists. For organizations still running 1607 in production, this is a known critical flaw with no vendor-provided fix.
HTTP.sys processes every incoming HTTP request at kernel level before it reaches any application. An integer overflow in parsing malformed HTTP/1.1 headers (specifically Content-Length values exceeding INT_MAX) allows an attacker to corrupt kernel heap memory and achieve arbitrary code execution at SYSTEM privilege — the highest privilege level on Windows. The EPSS score of 0.2275 indicates roughly a 23% probability of active exploitation within 30 days, and this probability will climb rapidly once public exploit code emerges.
For immediate defense: network-level filtering that rejects malformed HTTP/1.1 request headers with Content-Length values exceeding INT_MAX can block the exploit trigger without disabling HTTP.sys entirely. Alternatively, disable HTTP.sys completely via registry at HKLM\System\CurrentControlSet\Services\HTTP (set Start=4), but this breaks IIS, Windows Update, WinRM, and potentially other core services — severe operational impact that makes this a last resort. Enabling Driver Signature Enforcement through Secure Boot and HVCI blocks unsigned kernel driver exploitation but requires hardware compatibility validation.
Microsoft has issued emergency patches for critical kernel vulnerabilities in out-of-support systems before (WannaCry in 2017 covered Windows XP and Server 2003), but there's no guarantee they'll do so here. Organizations running 1607 should prioritize migration timelines over compensating controls as the only viable long-term risk reduction.
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