--- otrs/Kernel/System/HTMLUtils.pm (revision 3302)
+++ otrs/Kernel/System/HTMLUtils.pm (revision 3405)
@@ -818,7 +818,5 @@
 
     # add already existing "<a href" again
-    for my $Key ( keys %LinkHash ) {
-        ${$String} =~ s/$Key/$LinkHash{$Key}/g;
-    }
+    ${$String} =~ s/#{12}LinkHash-\d+#{12}/$LinkHash{$&} || $&/eg;
 
     # check ref && return result like called