CVE-1999-0418: Medium severity Sendmail Sendmail vulnerability
Denial of service in SMTP applications such as Sendmail, when a remote attacker (e.g. spammer) uses many "RCPT TO" commands in the same connection.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
Configure Sendmail to enforce a limit on the number of RCPT TO commands (recipients) accepted in a single SMTP connection; reject or temporarily defer sessions that exceed the configured limit.
Sendmail max_rcpt_per_connection = set a maximum number of RCPT TO commands accepted per SMTP connection (a small, reasonable limit) - Compensating control
Implement rate-limiting and connection controls at the network edge (firewall, load‑balancer, or SMTP proxy) to limit SMTP commands and concurrent connections per client IP; throttle or block clients that issue excessive RCPT TO commands.
- Operational
Monitor SMTP logs for excessive RCPT TO usage, identify abusive clients, and block or blacklist offending IP addresses; reload or restart Sendmail after applying configuration changes.
Event History
Frequently Asked Questions
What is the severity of CVE-1999-0418?
CVE-1999-0418 is classified as a denial of service vulnerability.
How do I fix CVE-1999-0418?
To fix CVE-1999-0418, it is recommended to update to the latest version of Sendmail that addresses this issue.
What applications are affected by CVE-1999-0418?
CVE-1999-0418 primarily affects SMTP applications such as Sendmail.
What is the impact of CVE-1999-0418?
The impact of CVE-1999-0418 is that it allows a remote attacker to monopolize SMTP resources, potentially leading to service outages.
How does CVE-1999-0418 work?
CVE-1999-0418 works by allowing a remote attacker to send numerous 'RCPT TO' commands within a single SMTP connection, exhausting server resources.