A heap buffer overflow vulnerability was discovered in Perl. 

When there are non-ASCII bytes in the left-hand-side of the `tr` operator, `S_do_trans_invmap` can overflow the destination pointer `d`.

   $ perl -e '$_ = "\x{FF}" x 1000000; tr/\xFF/\x{100}/;' 
   Segmentation fault (core dumped)

It is believed that this vulnerability can enable Denial of Service and possibly Code Execution attacks on platforms that lack sufficient defenses.