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 chunklength or a (2) large chunk->offset value in a PACKETPLAYERATTRIBUTECHUNK packet in the generichandleplayerattributechunk function in common/packets.c, and (3) a large packet->length value in the handleunitorders function in server/unithand.c.