CVE-2000-1090
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 · uneditedMicrosoft IIS for Far East editions 4.0 and 5.0 allows remote attackers to read source code for parsed pages via a malformed URL that uses the lead-byte of a double-byte character.
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 confidenceMicrosoft IIS 4.0 and 5.0 Far East editions contain an information disclosure vulnerability where malformed URLs utilizing the lead-byte of a double-byte character cause the server to return unparsed source code (e.g., ASP page source) instead of executing the server-side scripts.
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= 4.0= 5.0CVSS 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
- None
- Availability
- None
AV:N/AC:L/Au:N/C:P/I:N/A:N
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 checksWork through these to decide whether this CVE applies to you.
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Identify IIS versionRun 'iisweb.vbs -s W3SVC' or check the version from IIS Manager, or query the registry key HKLM\SYSTEM\CurrentControlSet\Services\W3SVC\Parameters\MajorVersion (value 4 for IIS 4.0, value 5 for IIS 5.0)Affected if Version equals 4.0 or 5.0
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Confirm Far East edition installationCheck the IIS installation language by examining the system locale settings or the IIS metabase for language pack indicators. On Far East systems (Japanese, Chinese, Korean Windows), the MUI or language packs for IIS would be present.Affected if Running a Japanese, Chinese, or Korean language version of Windows Server with IIS 4.0 or 5.0 installed
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Verify server is reachableAttempt to access the IIS server over HTTP/HTTPS using a browser or curl command to confirm it is responding to requests.Affected if The server is running and accessible on the network
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Test for double-byte URL handlingSend a request to an existing ASP page using a URL that includes a double-byte character sequence where the lead byte is crafted (for example, a URL with %XX patterns that mimic invalid double-byte sequences). Compare the response to the expected parsed output.Affected if The server returns unparsed ASP source code or discloses file contents instead of executing the script
The environment is affected if IIS version 4.0 or 5.0 is running on a Far East edition of Windows and the server responds to malformed double-byte URL sequences by returning source code instead of executed output.
Generated from the published advisory. Verify against your own configuration.
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 dataApply Microsoft security patches for this vulnerability. If patches are unavailable for these legacy systems, consider upgrading to a supported IIS version or implementing URL filtering to block malformed double-byte character sequences.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2000-1090 — 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.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2000-1090 in production — separate from our analysis above.
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
No notes yet
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- 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