BitTorrent and uTorrent allow remote attackers to inject command line parameters and execute arbitrary commands via a crafted URL using the (1) bittorrent or (2) magnet protocol.
Stack-based buffer overflow in (1) uTorrent 1.7.7 build 8179 and earlier and (2) BitTorrent 6.0.3 build 8642 and earlier allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a long Created By field in a .torrent file.