dbcve.org
Internet Information ServerApplication · Microsoft

CVE-2002-0071

HIGH · 7.5 CVSS v2.0 Published 2002-04-22
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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
Buffer overflow in the ism.dll ISAPI extension that implements HTR scripting in Internet Information Server (IIS) 4.0 and 5.0 allows attackers to cause a denial of service or execute arbitrary code via HTR requests with long variable names.

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

Buffer overflow vulnerability in the ism.dll ISAPI extension that handles HTR (HTML Template) scripting in IIS 4.0 and 5.0. Attackers can send HTR requests with overly long variable names to overflow a buffer, potentially causing denial of service or achieving remote code execution with elevated privileges.

MitigationDisable HTR scripting in IIS by removing or unregistering the ism.dll ISAPI extension, or apply the historical Microsoft patch (MS02-018). For legacy systems still running IIS 4.0/5.0, strongly consider migrating to supported IIS versions as these older versions are long past end-of-life.

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
Internet Information ServerApplication
Affected:= 4.0
Internet Information ServicesApplication
Affected:= 5.0

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
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
Partial

AV:N/AC:L/Au:N/C:P/I:P/A:P

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 IIS version
    Check the Windows system for IIS installation: For IIS 5.0/5.1, check 'C:\WINDOWS\system32\inetsrv' for metabase.bin or use 'iisweb.vbs /query' if available. For IIS 4.0, check 'C:\WINNT\system32\inetsrv'. Alternatively, check the Windows version: IIS 4.0 came with Windows NT 4.0 Option Pack, IIS 5.0 came with Windows 2000.
    Affected if The server is running IIS 4.0 or IIS 5.0 (these versions are long past end-of-life and vulnerable)
  2. Verify ism.dll exists
    Check if the ism.dll file exists at 'C:\WINDOWS\system32\ism.dll' or 'C:\WINNT\system32\ism.dll' using file explorer or command: 'dir /s C:\ism.dll' or 'dir /s D:\ism.dll'
    Affected if The ism.dll file exists on the server, indicating the HTR ISAPI extension is installed
  3. Check if HTR script mapping is enabled
    For IIS 5.0, open Internet Services Manager, right-click the website, select Properties, go to Home Directory tab, click Configuration, and check the Application Mappings list for '.htr' pointing to ism.dll. Alternatively, examine the metabase.xml file in 'C:\WINDOWS\system32\inetsrv' for a ScriptMap entry containing '.htr' and 'ism.dll'.
    Affected if An active script mapping exists for .htr extension pointing to ism.dll, meaning HTR processing is enabled
  4. Confirm ISAPI extension is allowed
    In IIS Manager, right-click the server or website, select Properties, click Master Properties under IIS section, go to Internet Services Manager, and verify the 'ism.dll' extension is listed under 'Web Service Extensions' with status 'Allowed'. For IIS 4.0, check the same in the Internet Information Server snap-in.
    Affected if The ism.dll ISAPI extension is listed and permitted to run, indicating HTR requests can be processed

A server is vulnerable if it runs IIS 4.0 or 5.0 with the ism.dll ISAPI extension installed AND the .htr script mapping enabled, allowing HTR requests to reach the vulnerable code path.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Disable HTR scripting in IIS by removing or unregistering the ism.dll ISAPI extension, or apply the historical Microsoft patch (MS02-018). For legacy systems still running IIS 4.0/5.0, strongly consider migrating to supported IIS versions as these older versions are long past end-of-life.

Fix this in Internet Information Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,090
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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-2002-0071 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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