PatchTheCVECVE-1999-1109: Sendmail before 8.10.0 allows remote attackers to cause a denial of service by sending a series of ETRN comman
CVE-1999-1109 is a medium-severity flaw (CVSS 5.0) affecting sendmail. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- EPSS top 6%: very likely to be exploited
- Public exploit reference
A fixed release or distro patch exists.
Risk facts
| CVSS score | 5.0 (Medium) |
| EPSS exploit chance | 7.2% (top 6%) |
| CISA exploited list | No |
| Published | 1999-12-22 |
| Last modified | 2026-06-16 |
Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Public exploits and detection
Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-1999-1109?
sendmail: upgrade to newer than 8.10.0. Exact commands for each OS are on this page.
Is CVE-1999-1109 being exploited?
CVE-1999-1109 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-1999-1109 affect?
CVE-1999-1109 affects sendmail. Severity is medium (CVSS 5.0). 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.
How urgent is CVE-1999-1109?
Priority 46/100. EPSS top 6%: very likely to be exploited; Public exploit reference
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