CVE-1999-0284
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 · uneditedDenial of service to NT mail servers including Ipswitch, Mdaemon, and Exchange through a buffer overflow in the SMTP HELO command.
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 confidenceBuffer overflow vulnerability in the SMTP HELO command allows remote attackers to cause denial of service on Windows NT mail servers including Ipswitch, Mdaemon, and Exchange by sending specially crafted oversized HELO commands.
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 dataall versions= 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
- 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 mail server productCheck system for IBM Lotus Domino or Microsoft Exchange Server installation. For Domino, look for Domino program files in typical installation paths (e.g., C:\Lotus\Domino). For Exchange, check Add/Remove Programs or registry for Microsoft Exchange Server entries.Affected if IBM Lotus Domino Mail Server of any version is installed, or Microsoft Exchange Server version 4.0 or 5.0 is installed
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Determine Microsoft Exchange versionIf Exchange is installed, check the version by examining the Exchange server binary files, registry keys under HKLM\SYSTEM\CurrentControlSet\Services\MSExchangeIS, or the Exchange System Manager interface if accessible.Affected if Microsoft Exchange Server version 4.0 or 5.0 is confirmed
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Verify SMTP service is enabledOn the mail server, check if the SMTP service is running. On Windows NT, use the Services control panel or run 'net start' command to list running services. Look for 'Simple Mail Transfer Protocol' or 'SMTP' service.Affected if SMTP service is enabled and running on the affected mail server
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Assess network exposureDetermine if the SMTP port (TCP 25) is accessible from external network locations. Use network scanning tools or check firewall rules to see if port 25 is open to untrusted networks.Affected if SMTP service is exposed to network (port 25 accessible from outside)
The environment is affected if IBM Lotus Domino Mail Server (any version) or Microsoft Exchange Server 4.0/5.0 is installed with SMTP service enabled and exposed.
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 vendor patches for the affected mail server products or upgrade to current supported versions; implement SMTP input validation at the network perimeter to filter abnormally long HELO commands.
- 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-1999-0284 — 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-1999-0284 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
- No spam, self-promotion, credentials, or personal data