CVE-1999-0412
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 · uneditedIn IIS and other web servers, an attacker can attack commands as SYSTEM if the server is running as SYSTEM and loading an ISAPI extension.
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 confidenceThis is a privilege escalation vulnerability in IIS and other web servers where ISAPI extensions execute with the same privileges as the web server process. If IIS runs as the SYSTEM account (the highest-privileged Windows account), a remote or local attacker who can trigger a vulnerable or malicious ISAPI extension can execute arbitrary commands with SYSTEM-level privileges, achieving full system compromise.
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= 4.0= 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 IIS installation and versionCheck the Windows system for installed IIS version by examining the system information or registry keys related to IIS (such as HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\InetStp). Compare your installed version to the affected versions: IIS 2.0, 3.0, or 4.0.Affected if The installed version is IIS 2.0, 3.0, or 4.0.
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Determine the IIS service accountOpen the Services console (services.msc), locate the IIS service (typically 'World Wide Web Publishing Service' or 'IIS Admin Service'), right-click and view Properties, then check the 'Log on as' field. Alternatively, use the command 'sc qc w3svc' or check via registry at HKLM\SYSTEM\CurrentControlSet\Services\W3SVC\ObjectName.Affected if The service is configured to run as 'LocalSystem' or 'SYSTEM' account.
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Verify if ISAPI extensions are enabledCheck the IIS metabase or configuration for ISAPI extension mappings. In IIS 4.0, open the IIS Manager, expand the web site, right-click on a directory, select 'Properties', go to 'Home Directory' or 'Virtual Directory' tab, click 'Configuration', and examine the 'App Mappings' tab for .dll extensions mapped to ISAPI filters or extensions.Affected if ISAPI extensions or filters are mapped and active on the server.
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Assess network exposureDetermine if the IIS server is directly exposed to untrusted networks or the internet, or if it is accessible to untrusted local users who could potentially trigger ISAPI extension execution.Affected if The server is accessible to untrusted users or networks who can make requests to trigger ISAPI extensions.
A system is affected if it runs IIS version 2.0, 3.0, or 4.0 with the web service running under the SYSTEM account and with ISAPI extensions enabled, allowing an attacker who can trigger an extension to gain SYSTEM-level privileges.
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 dataEnsure the web server does not run as SYSTEM; configure the IIS service to run under a least-privilege service account with limited local and domain permissions. Additionally, review and restrict ISAPI extensions to only those that are strictly necessary and trusted.
- Consultation2.0 h
- Implementation3.0 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-1999-0412 — 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-1999-0412 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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