CVE-2000-0024
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 · uneditedIIS does not properly canonicalize URLs, potentially allowing remote attackers to bypass access restrictions in third-party software via escape characters, aka the "Escape Character Parsing" 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 · moderate confidenceIIS fails to properly canonicalize URLs, allowing attackers to inject escape characters (such as %2e for dots) into URL paths to bypass access control checks implemented in third-party security software. This occurs because the server processes the escaped sequences differently than the security filters expect, enabling directory traversal and unauthorized access to restricted resources.
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= 3.0= 3.0CVSS 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
- Partial
- Availability
- None
AV:N/AC:L/Au:N/C:P/I:P/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 installed IIS versionOpen Command Prompt and run: inetmgr (IIS Manager) or check registry key HKLM\SYSTEM\CurrentControlSet\Services\W3SVC\Parameters\MajorVersionAffected if The version shows 4.0 exactly (MajorVersion = 4)
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Identify installed Site Server versionCheck Add/Remove Programs for 'Microsoft Site Server' or check installation directory for version informationAffected if Site Server 3.0 or Site Server Commerce 3.0 is installed
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Verify IIS service is runningOpen Services console (services.msc) and check if 'World Wide Web Publishing Service' status is Started, or run 'net start' and look for 'World Wide Web Publishing Service'Affected if IIS is actively running and serving HTTP requests
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Check for third-party URL filtering security toolsReview installed security software (firewall, URL scan filters, ISAPI filters) that performs access control based on URL paths. Check IIS management console for ISAPI filters under the web site propertiesAffected if Third-party security software performing URL-based access control is installed and enabled
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Test URL encoding handling (optional log review)Review IIS logs in %systemroot%\system32\LogFiles for requests containing encoded sequences like %2e (dot), %2f (slash), or %%2e that may indicate exploitation attemptsAffected if Suspicious encoded URL patterns appear in logs, indicating potential exploitation or vulnerability probing
Your environment is affected if IIS 4.0 or Site Server 3.0 is running and third-party security software performs URL-path-based access control without proper canonicalization handling.
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 (MS00-005) or upgrade to a patched version of IIS. Additionally, implement URL scanning at the perimeter and ensure third-party security tools perform proper URL decoding before applying access control rules.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2000-0024 — 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-2000-0024 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
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