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PHP 7.1.0/5.6.29 missing null byte checks for paths in exif_imagetype

Posted on 30 November -0001

<HTML><HEAD><TITLE>PHP 7.1.0/5.6.29 missing null byte checks for paths in exif_imagetype</TITLE><META http-equiv="Content-Type" content="text/html; charset=utf-8"></HEAD><BODY>Description:
------------
exif_imagetype doesn't ensure that pathnames lack NULL byte, which might allow attacker to manipulate the file path.

===============================================
Affected code:
PHP_FUNCTION(exif_imagetype)
{
    char *imagefile;
    size_t imagefile_len;
    php_stream * stream;
    int itype = 0;
 
    if (zend_parse_parameters(ZEND_NUM_ARGS(), "s", &imagefile, &imagefile_len) == FAILURE) { ⇐== THIS LINE
        return;
    }
===============================================

Test script:
---------------
<?php
var_dump(exif_imagetype("./image.pngx00.gallery.jpg"));
?>

Expected result:
----------------
expected parameter instead of string

Actual result:
--------------
$ php curl.php 
int(3)

Credit: Maksymilian from CXSECURITY.COM
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