Neither of these fix problems with less-thans or greater-thans or ampersands in the environment (not "environmental") variables. So, either dump them as text/plain:

#!/bin/sh
echo content-type: text/plain
echo
printenv
[download]

Or escape them properly:

#!/usr/bin/perl
use CGI ":all";
use HTML::Entities;
print header,
  start_html("env"),
  h1("env"), # can't have h2 without h1, c'mon!
  table({-border => 1},
    Tr([map td([map encode_entities($_), $_, $ENV{$_}]),
      sort keys %ENV])),
  end_html;
[download]

-- Randal L. Schwartz, Perl hacker