CVE-1999-0203
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 Sendmail, attackers can gain root privileges via SMTP by specifying an improper "mail from" address and an invalid "rcpt to" address that would cause the mail to bounce to a program.
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 confidenceSendmail vulnerability allowing root privilege escalation via SMTP. Attackers specify a malformed 'MAIL FROM' address combined with an invalid 'RCPT TO' address that triggers mail bouncing to an attacker-controlled program, achieving root access.
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= 8.6.10CVSS 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
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:N/AC:L/Au:N/C:C/I:C/A:C
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 Sendmail installationRun 'sendmail -V' or 'sendmail -d0.1' to display the version. On Linux, also try 'rpm -q sendmail' or 'dpkg -l sendmail'. Check for sendmail binary in /usr/sbin/sendmail or /etc/mail/Affected if The version displayed is 8.6.10 exactly, or falls within the 8.6.x range if broader vulnerable versions are suspected
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Verify the running mail serviceCheck if sendmail is listening on port 25 with 'netstat -tlnp | grep 25' or 'ss -tlnp | grep 25'. Also check running processes with 'ps aux | grep sendmail'Affected if Sendmail daemon is actively running and listening for SMTP connections on port 25
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Examine mail aliases configurationReview /etc/aliases (or /etc/mail/aliases) for any suspicious program paths or pipe-to-program syntax (e.g., '| /path/to/program'). Also check /etc/aliases.dbAffected if The aliases file contains pipe-to-program entries that could be exploited for privilege escalation if triggered by the malformed address sequence
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Check for vulnerable sendmail featuresReview sendmail configuration in /etc/sendmail.cf or /etc/mail/sendmail.mc for 'prog' or '| ' alias entries. Look for any address parsing rules that could be bypassedAffected if The configuration allows or fails to sanitize mail header manipulation that could redirect bounces to arbitrary programs
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Confirm product vendor and buildCheck if the binary is from the original Eric Allman Sendmail distribution: run 'file /usr/sbin/sendmail' and check any version banners on SMTP connection with 'telnet localhost 25'Affected if The binary is identified as Eric Allman Sendmail version 8.6.10 from the original vulnerable release
If your system runs Sendmail version 8.6.10 and has the mail service exposed, the vulnerability is present and exploitable via malformed MAIL FROM/RCPT TO address sequences.
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 dataModern sendmail versions have patched this vulnerability; upgrade to current sendmail releases or migrate to a modern mail transfer agent (Postfix, Exim) with proper address validation and restricted program execution policies.
- Consultation4.0 h
- Implementation16.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,960.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-1999-0203 — 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-1999-0203 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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