FreeBSD : sudo -- arbitrary command execution (1b725079-9ef6-11da-b410-000e0c2e438a)

Tavis Ormandy reports : The bash shell uses the value of the PS4 environment variable after expansion as a prefix for commands run in execution trace mode. Execution trace mode xtrace is normally set via bash's -x command line option or interactively by running 'set -o xtrace'. However, it may al...