The sosendto function in slirp/udp.c in QEMU before 2.1.2 allows local users to cause a denial of service (NULL pointer dereference) by sending a udp packet with a value of 0 in the source port and address, which triggers access of an uninitialized socket.
Exploitability
AV:LAC:LAu:NImpact
C:NI:NA:P2.1/AV:L/AC:L/Au:N/C:N/I:N/A:P