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AIX FTP server may not properly timeout ephemeral data ports

Vulnerability Note VU#118125

Original Release Date: 2005-07-07 | Last Revised: 2005-07-07


The IBM AIX FTP server may be vulnerable to a denial-of-service condition when passive data ports are not closed properly.


IBM AIX includes an FTP server, ftpd, which allows files to be transferred between hosts with the FTP protocol. This server is vulnerable to a condition where an attacker may be able to utilize all available ephemeral ports on the system. When the ephemeral port range is exhausted, no more ports are available for the system to use for an indefinite period of time, resulting in a system-wide network-based denial of service. Additionally, the memory usage caused by the sockets in use by ftpd may also create a local denial of service condition by limiting system resources available to other processes. AIX 5.1, 5.2, and 5.3 are affected.


A remote, authenticated user may be able to limit system and network resources and cause a denial-of-service condition. If anonymous FTP access is allowed, anonymous users are considered to be authenticated and may cause the same denial-of-service conditions.


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Vendor Information

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Updated:  July 07, 2005



Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.


Please contact IBM directly for information on resolution, fixes, patches, and workarounds.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

CVSS Metrics

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Thanks to Matt Mello and IBM for reporting this vulnerability.

This document was written by Ken MacInnis.

Other Information

CVE IDs: None
Severity Metric: 1.77
Date Public: 2005-07-07
Date First Published: 2005-07-07
Date Last Updated: 2005-07-07 20:08 UTC
Document Revision: 6

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