This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of RealNetworks RealPlayer. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the way RealPlayer handles audio encoded with the QCELP codec. The codec allows you to specify the 'block_size' that is used. This size is used to create an allocation to hold the data, but a hardcoded blocksize is later used to copy data into that allocation. This could lead to remote code execution under the context of the current user.