The user can run arbitrary code (just like eval $tainted_data). If you want to allow that, I suggest you use the Safe module (example RegexLab (a wxPerl version)).

If all you want to allow is backreferences, all you need is 1 eval, something like (untested): 

      my %backrefs;
      my( @backrefs ) = $with =~ /\$(\d+)/g;
      if ($modifiers =~ /g/) {
          $value =~ s/$this/
                        no strict 'refs';
                        @backrefs{@backrefs} = map { ${$_} } @backrefs
+;
                        my $ret = $with;
                        $ret =~ s'\$(\d+)'$backrefs{$1}'g;
                        undef %backrefs;
                        $ret; 
                    /ge;
      } else {
...

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In reply to Re: Security with /ee modifier by PodMaster
in thread Security with /ee modifier by richard5mith

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