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.