The dissect_sdp function in epan/dissectors/packet-sdp.c in the SDP dissector in Wireshark 1.12.x before 1.12.9 does not prevent use of a negative media count, which allows remote attackers to cause a denial of service (application crash) via a crafted packet.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.