CVE-1999-1109

sendmail < 8.10.0 - Denial of Service via ETRN Command Handling

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-1999-1109. PoCs published by Michal Zalewski.

AI-analyzed exploit summary This script exploits a denial-of-service vulnerability in Sendmail by repeatedly sending ETRN commands to exhaust system resources. It forks multiple telnet sessions to the target SMTP port (25) and kills them after a short delay to sustain the attack.

Description

Sendmail before 8.10.0 allows remote attackers to cause a denial of service by sending a series of ETRN commands then disconnecting from the server, while Sendmail continues to process the commands after the connection has been terminated.

Exploits (1)

exploitdb WORKING POC VERIFIED
by Michal Zalewski · bashdoslinux
https://www.exploit-db.com/exploits/19701

This script exploits a denial-of-service vulnerability in Sendmail by repeatedly sending ETRN commands to exhaust system resources. It forks multiple telnet sessions to the target SMTP port (25) and kills them after a short delay to sustain the attack.

Classification
Working Poc 95%
Attack Type
Dos
Complexity
Trivial
Reliability
Reliable
Target: Sendmail (versions affected by CVE-1999-1109)
No auth needed
Prerequisites: Network access to the target's SMTP port (25) · Sendmail server vulnerable to ETRN command abuse
devstral-2 · analyzed Feb 16, 2026 Full analysis →

References (4)

Core 4
Core References
Mailing List mailing-list x_refsource_bugtraq
http://marc.info/?l=bugtraq&m=94632241202626&w=2
Third Party Advisory, VDB Entry vdb-entry x_refsource_bid
http://www.securityfocus.com/bid/904
Mailing List mailing-list x_refsource_bugtraq
http://marc.info/?l=bugtraq&m=94780566911948&w=2
Third Party Advisory vdb-entry x_refsource_xf
http://www.iss.net/security_center/static/7760.php

Scores

EPSS 0.0717
EPSS Percentile 93.5%

Details

Status published
Products (1)
sendmail/sendmail < 8.10.0
Published Dec 22, 1999
Tracked Since Feb 18, 2026