Multiple heap-based buffer overflows in xvidcore/src/decoder.c in the xvidcore library in Xvid before 1.2.2 as used by Windows Media Player and other applications allow remote attackers to execute arbitrary code by providing a crafted macroblock (aka MBlock) number in a video stream in a crafted movie file that triggers heap memory corruption related to a \missing resync marker range check\ and the (1) decoder_iframe (2) decoder_pframe and (3) decoder_bframe functions.