Buffer overflow in Freeciv 2.1.0-beta1 and earlier, and SVN 15 Jul 2006 and earlier, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a (1) negative chunk_length or a (2) large chunk->offset value in a PACKET_PLAYER_ATTRIBUTE_CHUNK packet in the generic_handle_player_attribute_chunk function in common/packets.c, and (3) a large packet->length value in the handle_unit_orders function in server/unithand.c.