CVE-2000-0258
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 4.0 and 5.0 allows remote attackers to cause a denial of service by sending many URLs with a large number of escaped characters, aka the "Myriad Escaped Characters" 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 versions 4.0 and 5.0 contain a denial of service vulnerability where remote attackers can crash the server by submitting numerous HTTP requests containing URLs with an excessive number of escaped characters (e.g., %XX sequences). The vulnerability, known as 'Myriad Escaped Characters', exploits how IIS processes malformed URL 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= 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
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 checksWork through these to decide whether this CVE applies to you.
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Identify IIS versionCheck the IIS version by opening the Internet Information Services (IIS) Manager, right-clicking the server, selecting Properties, and viewing the version information. Alternatively, check the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\InetStp or use the command 'iisinfo' from the Windows resource kit.Affected if The version shows 4.0 or 5.0, indicating the server is running a vulnerable version.
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Confirm IIS service is runningVerify that the IIS service (World Wide Web Publishing Service) is running by opening Services.msc and checking the status of 'World Wide Web Publishing Service', or run 'net start' in command prompt to list running services.Affected if IIS is actively running and accepting HTTP requests, making it susceptible to the malformed URL DoS.
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Check for external HTTP exposureDetermine if the IIS server is directly exposed to external networks by reviewing network configuration, firewall rules, or by attempting to access the server from an external IP address using a browser or curl request.Affected if The IIS server is reachable from untrusted networks, meaning remote attackers can send the malicious requests.
If the server runs IIS version 4.0 or 5.0, has the WWW service running, and is network-accessible, the environment is affected by this vulnerability.
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 the appropriate Microsoft security patch for this vulnerability, or consider upgrading to a newer IIS version with continued security support. Implement web application firewall rules or rate limiting as an interim compensating control.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2000-0258 — 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-2000-0258 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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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.
- 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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