CVE-1999-0253
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 3.0 with the iis-fix hotfix installed allows remote intruders to read source code for ASP programs by using a %2e instead of a . (dot) in the URL.
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 confidenceIIS 3.0 with the iis-fix hotfix installed contains a path traversal vulnerability where URL-encoding a dot as %2e bypasses security checks, allowing remote attackers to retrieve the raw source code of ASP files instead of having them parsed and executed by the server.
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= 3.0= 1.0= 2.0CVSS 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
- 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 checksWork through these to decide whether this CVE applies to you.
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Identify installed IIS versionCheck the IIS version through the IIS Manager snap-in, or by viewing the properties of the WWW service in the Windows NT Option Pack, or by checking the version information of the inetinfo.exe executable in the system32 directoryAffected if The installed version is 1.0, 2.0, or 3.0 (specifically Microsoft Internet Information Server 3.0 or Microsoft Internet Information Services 1.0/2.0)
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Confirm iis-fix hotfix presenceThe vulnerability exists specifically in IIS 3.0 with the iis-fix hotfix installed. Check system information or the list of installed hotfixes for the iis-fix hotfix on the IIS 3.0 serverAffected if IIS 3.0 is running and the iis-fix hotfix has been applied to this installation
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Verify ASP functionality is enabledThe vulnerability allows retrieval of raw ASP source code instead of execution. Confirm that ASP scripts are enabled and configured on the IIS server by checking the script mappings in the IIS ManagerAffected if ASP script mapping is registered and enabled on the server (files with .asp extension are mapped to the ASP DLL)
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Test for %2e URL encoding bypassSend a request to the server using a URL with %2e encoded dot to attempt to access an ASP file. For example: request /scripts/file%2easp or similar path with %2e replacing a dot in the filename. If the server returns the raw ASP source code instead of executing it, the vulnerability is presentAffected if The server returns unparsed ASP source code content (visible script tags, VBScript/JScript code) in the HTTP response when using %2e encoding
The environment is affected if running IIS versions 1.0, 2.0, or 3.0 with the iis-fix hotfix installed and ASP scripts enabled, where a request with %2e URL-encoding returns raw ASP 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 updates for IIS 3.0 or, given the severity and age of this vulnerability, migrate to a supported version of IIS or a modern web server platform with current security patches.
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-1999-0253 — 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-1999-0253 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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