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AOL Nullsoft Winamp Ultravox 'ultravox-max-msg' Header Heap Overflow Vulnerability



Ultravox is a streaming media technology developed by AOL for delivering and publishing streaming media such as music files. The WinAmp media player has support for this protocol. More information about WinAmp is available at the following site:



Remote exploitation of a heap-based buffer overflow vulnerability in the Ultravox protocol handler of AOL Corp.'s Nullsoft Winamp media player could allow an attacker to execute arbitrary code in the context of the currently logged in user.

Due to an error in the handling of the 'ultravox-max-msg' header, it is possible for a malicious server to cause the Winamp client to allocate a very small amount of space and then try fill it with a large amount of server supplied date, potentially overwriting values which will lead to code execution.


Successful exploitation of this vulnerability would allow a remote attacker to execute code in the context of the user who started Winamp. In order to exploit this vulnerability, the attacker would need to cause or convince the intended victim to connect to a malicious server. This could be accomplished by embedding a link in a web page to a playlist file, a 'shout:' URI or a 'uvox:' URI, which are automatically by Winamp from Internet Explorer. Alternatively, one of these items could be placed in a playlist file. The attacker would have no way to force the user to open the content they have supplied.


iDefense has confirmed the existence of this vulnerability in version 5.24 and 5.3 of Nullsoft Winamp. Previous versions also may be affected.


iDefense is currently unaware of any effective workarounds for this vulnerability.


Nullsoft has released version 5.31 of Winamp to address this problem.


A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not been assigned yet.


10/19/2006 Initial vendor notification
10/25/2006 Initial vendor response
10/25/2006 Coordinated public disclosure


The discoverer of this vulnerability wishes to remain anonymous.

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Copyright © 2006 Verisign, Inc.

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