Since there is no fixed, I was tasked to get this to work..  Here is the 
workaround I created and the code has been in the production for a year.  I 
found it works well.  Also, when Microsoft utilize subjectAltName as 
UserPrincipalName value to integrate smart card authentication with Active 
Directory.  Getting this to work is very important for web applications.

1) create a directory USERCERT under your PHP script folder.  allow this folder 
upload files via the web browser.
2) copy paste the following codes to your php script which is used to read the 
certificate information.
        $yourcn = $_SERVER['SSL_CLIENT_S_DN_CN']; 
        $filename=str_replace('(Affiliate)', '', str_replace(' ', '.', 
$yourcn)).rand().".cer";
	$file1 = $_SERVER['SSL_CLIENT_CERT'];
	file_put_contents('USERCERT/'.$filename, $file1);
	$cmd1 = "openssl asn1parse  -in USERCERT/$filename | grep -A 1 'Subject 
Alternative Name' | cut -f1 -d':' | tail -1";
	$output1 = shell_exec($cmd1);
	$output3 = shell_exec("sh testname.sh '$output1' '$filename'");
    
   so. the result of $output3 will be the subjectAltName.  This value is the 
UserPrincipalName in Active Directory.

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3) create a shell script, name testname.sh and place under the same directory as 
your php script at the step 2.  Please make this testname.sh with 644 permission 
in Linux.  Here is the content of testname.sh
    openssl asn1parse -strparse $1 -in USERCERT/$2 | grep -A 2 "Microsoft 
Universal Principal Name" | cut -f4 -d":" |tail -1


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Hope this works for you.