The dissectcapwapdata function in epan/dissectors/packet-capwap.c in the CAPWAP dissector in Wireshark 1.6.x before 1.6.16 and 1.8.x before 1.8.8 incorrectly uses a -1 data value to represent an error condition, which allows remote attackers to cause a denial of service (application crash) via a crafted packet.