FFmpeg before 0.5.4, as used in MPlayer and other products, allows remote attackers to cause a denial of service (heap memory corruption and application crash) or possibly execute arbitrary code via a malformed RealMedia file.
http://www.debian.org/security/2011/dsa-2306
http://www.mandriva.com/security/advisories?name=MDVSA-2011:061
http://www.mandriva.com/security/advisories?name=MDVSA-2011:062
http://www.mandriva.com/security/advisories?name=MDVSA-2011:089
http://www.mandriva.com/security/advisories?name=MDVSA-2011:114
http://www.securityfocus.com/bid/47149