Unusual but valid headers in requests are not available to PHP when running via CGI

Description

The following code:

<?php
print_r($_SERVER);

Requested with:

curl -s -H 'X-Test: 1' -H 'X-%%Test%%: 1' 'http://127.0.0.1/' | grep 'HTTP_'

Resulted in this output:

[HTTP_X_TEST] => 1
[HTTP_ACCEPT] => */*
[HTTP_USER_AGENT] => curl/7.83.1
[HTTP_HOST] => 127.0.0.1

But I expected this output instead:

[HTTP_X_TEST] => 1
[HTTP_X_%%TEST%%] => 1
[HTTP_ACCEPT] => */*
[HTTP_USER_AGENT] => curl/7.83.1
[HTTP_HOST] => 127.0.0.1

This appears to be unique to CGI, or alternatively mod_php is immune.

PHP Version

PHP 8.1.26

Operating System

Alpine Linux 3.18

Riproduci la richiesta con PHP 8.1.26 su Alpine Linux 3.18 tramite CGI e verifica come CGI popola $SERVER, confrontando il risultato con mod_php. Il lavoro è completato quando l’header insolito X-%%Test%% è disponibile come HTTP_X%%TEST%% e gli header esistenti rimangono disponibili.