CVE-2003-0225
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 · uneditedThe ASP function Response.AddHeader in Microsoft Internet Information Server (IIS) 4.0 and 5.0 does not limit memory requests when constructing headers, which allow remote attackers to generate a large header to cause a denial of service (memory consumption) with an ASP page.
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 confidenceThe ASP Response.AddHeader function in Microsoft IIS 4.0 and 5.0 does not impose limits on memory requests when constructing HTTP headers, allowing remote attackers to send excessively large headers that cause memory exhaustion and denial of service.
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
- None
- Integrity
- None
- Availability
- Partial
AV:N/AC:L/Au:N/C:N/I:N/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.
-
Identify IIS versionOpen IIS Manager and view server properties, or check the file version of %SystemRoot%\system32\inetsrv\inetinfo.exe. In registry, examine HKLM\SYSTEM\CurrentControlSet\Services\W3SVC\Parameters\MajorVersionAffected if The version is 4.0 or 5.0
-
Verify ASP is enabledIn IIS Manager, expand the Web Service Extensions node and check if Active Server Pages shows a status of AllowedAffected if ASP is permitted and active for the affected site or default application
-
Confirm header limits are not enforcedCheck registry key HKLM\System\CurrentControlSet\Services\HTTP\Parameters for MaxClientRequestBuffer or HeaderWaitTimeout values. If absent or set to very high values, no effective limit existsAffected if No header size limits are configured or limits exceed reasonable bounds (such as >16KB)
-
Inspect current header behaviorReview IIS logs or capture network traffic to observe the size of incoming HTTP headers being processed. Look for requests with unusually large header fieldsAffected if The server accepts and processes headers without rejecting oversized requests
You are affected if you are running IIS 4.0 or 5.0 with ASP enabled and without enforced header size limits, allowing unbounded HTTP header memory allocation.
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 available Microsoft patches for this vulnerability, or implement a front-end load balancer/reverse proxy to enforce header size limits and block requests with abnormally large headers.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2003-0225 — 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-2003-0225 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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
- No spam, self-promotion, credentials, or personal data