The BEGIN regular expression in the awk script detector in magic/Magdir/commands in file before 5.15 uses multiple wildcards with unlimited repetitions, which allows context-dependent attackers to cause a denial of service (CPU consumption) via a crafted ASCII file that triggers a large amount of backtracking, as demonstrated via a file with many newline characters.
http://bugs.gw.com/view.php?id=164
http://rhn.redhat.com/errata/RHSA-2014-1765.html
http://support.apple.com/kb/HT6443
http://www.debian.org/security/2014/dsa-2873
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=703993
https://github.com/file/file/commit/ef2329cf71acb59204dd981e2c6cce6c81fe467c