Public Vulnerability Reports

Multiple Vendor FLAC Library Multiple Integer Overflow Vulnerabilities



Free Lossless Audio Codec (FLAC) is a popular file format for audio data compression. AOL Corp.'s Winamp media player has support for the FLAC format. More information about FLAC and Winamp is available at the following URLs.


Remote exploitation of multiple integer overflow vulnerabilities in libFLAC, as included with various vendor's software distributions, allows attackers to execute arbitrary code in the context of the currently logged in user.

These vulnerabilities specifically exist in the handling of malformed FLAC media files. In each case, an integer overflow can occur while calculating the amount of memory to allocate. As such, insufficient memory is allocated for the data that is subsequently read in from the file, and a heap based buffer overflow occurs.


Exploitation allows remote attackers to execute arbitrary code in the context of the user attempting to play the media file. Exploitation requires that an attacker persuade a targeted user into opening a malformed FLAC file.


iDefense has confirmed the existence of these vulnerabilities libFLAC 1.2.0, as well as the version of libFLAC included in in the full 5.35 version Winamp. Previous versions of libFLAC may also be vulnerable. The lite version of Winamp does not include support for the FLAC file format, and as such is not vulnerable.


For Winamp users, it is possible to remove support for the FLAC file format by uninstalling the FLAC input plug-in.


The FLAC maintainers have released version 1.2.1 of FLAC to address these vulnerabilities. AOL Corp. has addressed this vulnerability in version 5.5 of Winamp. For more information see the FLAC change log at the following URL.


The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2007-4619 to this issue. This is a candidate for inclusion in the CVE list (, which standardizes names for security problems.


08/29/2007 Initial vendor notification
08/29/2007 Initial vendor response
10/11/2007 Coordinated public disclosure


This vulnerability was reported to iDefense by Sean de Regge.

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Copyright © 2007 Verisign, Inc.

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