Public Vulnerability Reports

Samba 3.x SMBD Remote Denial of Service Vulnerability



Samba is a software suite that provides file and print services to
SMB/CIFS clients, such as Microsoft Windows platforms. For more
information see:


An unauthenticated remote user can cause a resource exhaustion attack by
sending multiple malformed requests to an affected server. Each request
spawns a new process, which enters an infinite loop.


This attack takes very little bandwidth to cause the machine to stop
responding. Each request from the exploit tested was only 358 bytes, and
a Redhat Fedora Core 1 machine with 512 megabytes of RAM and 512
megabytes of swap took fewer than 4000 requests to render it unusable.


iDEFENSE has confirmed Samba 3.0.2 and 3.0.4 are vulnerable.

The vendor has confirmed that Samba 3.0.x prior to and including v3.0.6
are vulnerable.


Restricting access to the server by using the "hosts allow" setting in
smb.conf and/or applying firewall rules may help mitigate this


The patch file for Samba 3.0.5 addressing [the] bug
(samba-3.0.5-DoS.patch) can be downloaded from:


The Common Vulnerabilities and Exposures (CVE) project has assigned the
names CAN-2004-0807 to these issues. This is a candidate for inclusion
in the CVE list (, which standardizes names for
security problems.


09/02/2004    Initial vendor notification
09/02/2004    iDEFENSE clients notified
09/02/2004    Vendor response
09/13/2004    Coordinated public disclosure


The discoverer wishes to remain anonymous.

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Copyright © 2004 Verisign, Inc.

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at the time of publishing based on currently available information. Use
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