App::Ack versions before 3.10.0 for Perl allow memory exhaustion via an unbounded context value in a project .ackrc. ack searches up the directory hierarchy from the current directory for a project .ackrc and loads its options. The -B and -C context options accepted any positive integer, and ack sized the before-context buffer to that value, so a project .ackrc setting --before-context=100000000 made ack allocate a buffer of 100 million elements. A project .ackrc committed to an untrusted repository can abort ack with an out-of-memory condition.
App::Ack versions before 3.10.0 for Perl allow memory exhaustion via an unbounded context value in a project .ackrc