Fabric before 1.1.0 allows local users to overwrite arbitrary files via a symlink attack on (1) a /tmp/fab.*.tar file or (2) certain other files in the top level of /tmp/.
Exploitability
AV:LAC:MAu:NImpact
C:PI:PA:P4.4/AV:L/AC:M/Au:N/C:P/I:P/A:P