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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 10 Aug 2022.
Windows 7Operating system · Microsoft

CVE-2015-1635

CRITICAL · 9.8 CVSS v3.1 Published 2015-04-14
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
In the wild High EPSS Public exploit Remotely reachable No privileges Zero-click Patch available

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
HTTP.sys in Microsoft Windows 7 SP1, Windows Server 2008 R2 SP1, Windows 8, Windows 8.1, and Windows Server 2012 Gold and R2 allows remote attackers to execute arbitrary code via crafted HTTP requests, aka "HTTP.sys Remote Code Execution Vulnerability."

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 · high confidence

HTTP.sys kernel-mode driver contains a vulnerability that allows remote attackers to execute arbitrary code via specially crafted HTTP requests. The vulnerability is triggered when HTTP.sys parses malformed HTTP requests, leading to memory corruption that can be exploited for RCE.

MitigationApply Microsoft security update MS15-034 (or subsequent cumulative updates) to affected Windows systems. If immediate patching is not possible, consider disabling HTTP/2 support at the IIS level or deploying a WAF to filter malicious requests.

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 7Operating system
Affected:all versions
Windows 8Operating system
Affected:all versions
Windows 8.1Operating system
Affected:all versions
Windows Server 2008Operating system
Affected:= r2
Windows Server 2012Operating system
Affected:all versions= r2

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.

  1. Identify Windows version
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to confirm the installed Windows version
    Affected if Version is NOT Windows 7, Windows 8, Windows 8.1, Windows Server 2008 R2, Windows Server 2012, or Windows Server 2012 R2 (these are the only affected versions)
  2. Confirm IIS is installed
    Check for IIS by looking for the 'IIS World Wide Web Publishing Service' in services.msc or run 'Get-Service W3SVC' in PowerShell
    Affected if IIS is not installed (http.sys is only exposed when IIS is running)
  3. Verify HTTP.sys driver is loaded
    Run 'sc query http' or check that the HTTP.sys driver (http.sys) is listed in the list of loaded drivers via 'driverquery | findstr http'
    Affected if HTTP.sys driver is not loaded (the vulnerable driver is not active)
  4. Check if MS15-034 patch is installed
    Run 'Get-HotFix -Id KB3042553' in PowerShell or check Windows Update history for security update KB3042553
    Affected if The patch KB3042553 is NOT installed on an affected Windows version with IIS running

A system is affected if it runs a vulnerable Windows version (7, 8, 8.1, Server 2008 R2, Server 2012, or Server 2012 R2) with IIS installed and the MS15-034 security update (KB3042553) has not been applied.

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
Patch available Apply the vendor patch
Vendor patch docs.microsoft.com →
Interim mitigation

Apply Microsoft security update MS15-034 (or subsequent cumulative updates) to affected Windows systems. If immediate patching is not possible, consider disabling HTTP/2 support at the IIS level or deploying a WAF to filter malicious requests.

Recommended fix High confidence

Apply Microsoft Security Update MS15-034 (KB3042553)

  1. Apply Microsoft Security Update MS15-034 to patch the HTTP.sys vulnerability
  2. On affected Windows systems, install the MS15-034 security update from Windows Update or the Microsoft Download Center
  3. Verify the patch was installed successfully by checking Windows Update history or reviewing installed updates
  4. For systems that are no longer supported (Windows 7, Windows Server 2008 R2), consider migrating to a supported operating system version
  5. Ensure HTTP.sys is not exposed to untrusted networks if patching is not possible as a temporary mitigation
Caveat Windows 7 and Windows Server 2008 R2 reached end of support in January 2020; Windows 8.1 reached end of support in January 2023; Windows Server 2012 and 2012 R2 have varying support timelines - consider migrating to supported versions

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

Fix this in Windows 7 Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
Get it fixed fast

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

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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-2015-1635 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