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 qcpfformat.dll, which is responsible for parsing QCP media files. The process creates a static 256 byte allocation on the heap and trusts a user-supplied counter from the file within a memory copy loop. As the source data is also user-supplied from the file, this can be abused by a remote attacker to execute arbitrary code running in the context of the web browser.