xine-lib 1.1.12, and other 1.1.15 and earlier versions, relies on an untrusted input value to determine the memory allocation and does not check the result for (1) the MATROSKA_ID_TR_CODECPRIVATE track entry element processed by demux_matroska.c; and (2) PROP_TAG, (3) MDPR_TAG, and (4) CONT_TAG chunks processed by the real_parse_headers function in demux_real.c; which allows remote attackers to cause a denial of service (NULL pointer dereference and crash) or possibly execute arbitrary code via a crafted value.