CVE-2004-0042
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 · uneditedvsftpd 1.1.3 generates different error messages depending on whether or not a valid username exists, which allows remote attackers to identify valid usernames.
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 confidencevsftpd 1.1.3 exhibits a user enumeration vulnerability where the server returns distinct error messages for valid versus invalid usernames during authentication. This allows remote attackers to systematically identify valid user accounts on the FTP server by observing the differing responses.
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= 1.1.3CVSS 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
- None
- Availability
- None
AV:N/AC:L/Au:N/C:P/I:N/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 vsftpd versionRun 'vsftpd -v' or check package manager (rpm -q vsftpd, dpkg -l vsftpd) to determine the exact version installedAffected if Version is 1.1.3 of Beasts vsftpd
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Confirm FTP service is runningCheck if the FTP daemon is active and listening on port 21 using commands like 'netstat -tlnp | grep :21' or 'ss -tlnp | grep :21'Affected if vsftpd is actively serving FTP connections
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Test authentication response with invalid usernameAttempt FTP login with a clearly non-existent user (e.g., USER nonexistent123) and record the exact error message returnedAffected if Server returns any error message for the invalid username
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Test authentication response with valid usernameAttempt FTP login with a known valid system account (e.g., USER root or USER admin) and record the exact error message returnedAffected if Server returns an error message that is different from the invalid username response
A user is affected if vsftpd version 1.1.3 is running and the server produces distinct error responses that differ between valid and invalid usernames during authentication, allowing user account enumeration.
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 dataUpgrade vsftpd to a version that uniformizes authentication error messages, or modify the application to return identical error responses regardless of username validity.
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2004-0042 — 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-2004-0042 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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