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I am trying to display some data with the use of PHP. But there always is nothing displayed with the following error:
Access to fetch at [PHP-File on my Website] from origin [My Website] has been blocked by CORS policy: Response to preflight request doesn't pass access control check: It does not have HTTP ok status.
I already edited the .htaccess file, it looks like this:
Header add Access-Control-Allow-Origin: *
Header add Access-Control-Allow-Methods: 'GET, POST, PATCH, PUT, DELETE, OPTIONS'
Header add Access-Control-Allow-Headers: 'Origin, Content-Type, X-Auth-Token, Authorization, X-Requested-With, Content-Type, Accept, Access-Control-Request-Headers, Access-Control-Request-Method'
All these parameters are displayed in my response header, but still the preflight check fails.
I am trying to set up a sandbox API for development, so users can hit the API from local dev machines. But am running into what I believe is a CORS issue.
At first all traffic was being blocked by the CORS policy, so I added the following to my .htaccess file:
Header set Access-Control-Allow-Origin "*"
Header set Access-Control-Allow-Headers "origin, x-requested-with, content-type"
Header set Access-Control-Allow-Methods "PUT, GET, POST, DELETE, OPTIONS"
After that, I can see that not only am I getting a 200 status, but my payload is being correctly sent. Good stuff!
However .. The PHP file that is requesting -> /myp/index.php contains ONLY the following:
<?php
print_r ($_POST);
echo "Done";
And the response from the above POST comes back:
Array
(
)
Done
I have read MANY posts that all say the same thing: Add the following to the PHP file:
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Methods: PUT, GET, POST, DELETE, OPTIONS");
header("Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, X-Auth-Token, Accept");
header ("Access-Control-Expose-Headers: Content-Length, X-JSON");
But when I add that to the PHP file .. I get another CORS error..
WITH CORS RULES APPLIED TO PHP FILE
What else do I need to be looking at? Why is CORS denied when I throw the PHP headers in, but is OK without them? And why does PHP not accept the POST variables when CORS shows a 200 and I can verify post data sent?
And the response from the above POST comes back:
The key there is that you do get the response and you don’t get a CORS error.
So the problem isn’t CORS and you shouldn’t touch your CORS headers.
(When you add the headers with PHP, Apache merges them with the headers you tell it to add and you end up with Access-Control-Allow-Origin: *, * which, as the error message says, is invalid).
If the $_POST superglobal is empty, it is because you aren’t POSTing data in a format that PHP will decode automatically.
Most likely, you are sending a JSON payload in which case you need to either read the body from STDIN and parse it yourself or change the data you are sending to be in a format that PHP does support (URL Encoded or Multipart Encoded).
const body = new URLSearchParams({ foo: 1, bar: "hello, world" });
const url = "http://example.com";
const response = await fetch(url, { body });
I have a very stranger behaviour when trying to set the Access-Control-Allow-Credentials on my pages to allow CORS.
To sum-up: my "Allow-Credentials" header sent with PHP seems to be taken into account only if the same header is sent by the server itself... in which case the header becomes "true, true" which is not an accepted value...
I'm using Laravel and have a middleware that adds the relevant headers to the relevant pages:
header('Access-Control-Allow-Origin: mysite.test'));
header('Access-Control-Allow-Headers: Content-Type, X-Auth-Token, X-CSRF-Token, X-Requested-With, Authorization, Origin');
header('Access-Control-Allow-Methods: GET, POST, PUT, PATCH, DELETE');
header('Access-Control-Allow-Credentials: true');
When my page tries to send an Ajax request, the browser console outputs the following:
(...) The value of the 'Access-Control-Allow-Credentials' header in the response is '' which must be 'true' when the request's credentials mode is 'include'.
After trying a few things to debug, I added the header to the nginx conf itself:
add_header Access-Control-Allow-Credentials "true";
And that's where I feel really helpless.. the output of the browser is now:
(...) The value of the 'Access-Control-Allow-Credentials' header in the response is 'true, true' which must be 'true' when the request's credentials mode is 'include'.
The same code works perfectly fine on another server with same .conf file for nginx.. Any idea where I can look to figure all this out?
I have a simple PHP script that I am attempting a cross-domain CORS request:
<?php
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Headers: *");
...
Yet I still get the error:
Request header field X-Requested-With is not allowed by Access-Control-Allow-Headers
Anything I'm missing?
Handling CORS requests properly is a tad more involved. Here is a function that will respond more fully (and properly).
/**
* An example CORS-compliant method. It will allow any GET, POST, or OPTIONS requests from any
* origin.
*
* In a production environment, you probably want to be more restrictive, but this gives you
* the general idea of what is involved. For the nitty-gritty low-down, read:
*
* - https://developer.mozilla.org/en/HTTP_access_control
* - https://fetch.spec.whatwg.org/#http-cors-protocol
*
*/
function cors() {
// Allow from any origin
if (isset($_SERVER['HTTP_ORIGIN'])) {
// Decide if the origin in $_SERVER['HTTP_ORIGIN'] is one
// you want to allow, and if so:
header("Access-Control-Allow-Origin: {$_SERVER['HTTP_ORIGIN']}");
header('Access-Control-Allow-Credentials: true');
header('Access-Control-Max-Age: 86400'); // cache for 1 day
}
// Access-Control headers are received during OPTIONS requests
if ($_SERVER['REQUEST_METHOD'] == 'OPTIONS') {
if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_METHOD']))
// may also be using PUT, PATCH, HEAD etc
header("Access-Control-Allow-Methods: GET, POST, OPTIONS");
if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']))
header("Access-Control-Allow-Headers: {$_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']}");
exit(0);
}
echo "You have CORS!";
}
Security Notes
Check the HTTP_ORIGIN header against a list of approved origins.
If the origin isn't approved, then you should deny the request.
Please read the spec.
TL;DR
When a browser wants to execute a cross-site request it first confirms that this is okay with a "pre-flight" request to the URL. By allowing CORS you are telling the browser that responses from this URL can be shared with other domains.
CORS does not protect your server. CORS attempts to protect your users by telling browsers what the restrictions should be on sharing responses with other domains. Normally this kind of sharing is utterly forbidden, so CORS is a way to poke a hole in the browser's normal security policy. These holes should be as small as possible, so always check the HTTP_ORIGIN against some kind of internal list.
There are some dangers here, especially if the data the URL serves up is normally protected. You are effectively allowing browser content that originated on some other server to read (and possibly manipulate) data on your server.
If you are going to use CORS, please read the protocol carefully (it is quite small) and try to understand what you're doing. A reference URL is given in the code sample for that purpose.
Header security
It has been observed that the HTTP_ORIGIN header is insecure, and that is true. In fact, all HTTP headers are insecure to varying meanings of the term. Unless a header includes a verifiable signature/hmac, or the whole conversation is authenticated via TLS, headers are just "something the browser has told me".
In this case, the browser is saying "an object from domain X wants to get a response from this URL. Is that okay?" The point of CORS is to be able to answer, "yes I'll allow that".
I got the same error, and fixed it with the following PHP in my back-end script:
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: GET, POST');
header("Access-Control-Allow-Headers: X-Requested-With");
Access-Control-Allow-Headers does not allow * as accepted value, see the Mozilla Documentation here.
Instead of the asterisk, you should send the accepted headers (first X-Requested-With as the error says).
Update:
* is now accepted is Access-Control-Allow-Headers.
According to MDN Web Docs 2021:
The value * only counts as a special wildcard value for requests without credentials (requests without HTTP cookies or HTTP authentication information). In requests with credentials, it is treated as the literal header name * without special semantics. Note that the Authorization header can't be wildcarded and always needs to be listed explicitly.
Many description internet-wide don't mention that specifying Access-Control-Allow-Origin is not enough. Here is a complete example that works for me:
<?php
if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: POST, GET, DELETE, PUT, PATCH, OPTIONS');
header('Access-Control-Allow-Headers: token, Content-Type');
header('Access-Control-Max-Age: 1728000');
header('Content-Length: 0');
header('Content-Type: text/plain');
die();
}
header('Access-Control-Allow-Origin: *');
header('Content-Type: application/json');
$ret = [
'result' => 'OK',
];
print json_encode($ret);
I've simply managed to get dropzone and other plugin to work with this fix (angularjs + php backend)
header('Access-Control-Allow-Origin: *');
header("Access-Control-Allow-Credentials: true");
header('Access-Control-Allow-Methods: GET, PUT, POST, DELETE, OPTIONS');
header('Access-Control-Max-Age: 1000');
header('Access-Control-Allow-Headers: Origin, Content-Type, X-Auth-Token , Authorization');
add this in your upload.php or where you would send your request (for example if you have upload.html and you need to attach the files to upload.php, then copy and paste these 4 lines).
Also if you're using CORS plugins/addons in chrome/mozilla be sure to toggle them more than one time,in order for CORS to be enabled
If you want to create a CORS service from PHP, you can use this code as the first step in your file that handles the requests:
// Allow from any origin
if(isset($_SERVER["HTTP_ORIGIN"]))
{
// You can decide if the origin in $_SERVER['HTTP_ORIGIN'] is something you want to allow, or as we do here, just allow all
header("Access-Control-Allow-Origin: {$_SERVER['HTTP_ORIGIN']}");
}
else
{
//No HTTP_ORIGIN set, so we allow any. You can disallow if needed here
header("Access-Control-Allow-Origin: *");
}
header("Access-Control-Allow-Credentials: true");
header("Access-Control-Max-Age: 600"); // cache for 10 minutes
if($_SERVER["REQUEST_METHOD"] == "OPTIONS")
{
if (isset($_SERVER["HTTP_ACCESS_CONTROL_REQUEST_METHOD"]))
header("Access-Control-Allow-Methods: POST, GET, OPTIONS, DELETE, PUT"); //Make sure you remove those you do not want to support
if (isset($_SERVER["HTTP_ACCESS_CONTROL_REQUEST_HEADERS"]))
header("Access-Control-Allow-Headers: {$_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']}");
//Just exit with 200 OK with the above headers for OPTIONS method
exit(0);
}
//From here, handle the request as it is ok
CORS can become a headache, if we do not correctly understand its functioning. I use them in PHP and they work without problems. reference here
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Credentials: true");
header("Access-Control-Max-Age: 1000");
header("Access-Control-Allow-Headers: X-Requested-With, Content-Type, Origin, Cache-Control, Pragma, Authorization, Accept, Accept-Encoding");
header("Access-Control-Allow-Methods: PUT, POST, GET, OPTIONS, DELETE");
This much code works down for me when using angular 4 as the client side and PHP as the server side.
header("Access-Control-Allow-Origin: *");
this should work
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Headers: X-Requested-With, Content-Type, Origin, Cache-Control, Pragma, Authorization, Accept, Accept-Encoding");
I used these 5 headers and after that solved the cors error(backend: PHP, Frontend: VUE JS)
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: GET, PUT, POST, DELETE, OPTIONS, post, get');
header("Access-Control-Max-Age", "3600");
header('Access-Control-Allow-Headers: Origin, Content-Type, X-Auth-Token');
header("Access-Control-Allow-Credentials", "true");
add this code in .htaccess
add custom authentication key's in header like app_key,auth_key..etc
Header set Access-Control-Allow-Origin "*"
Header set Access-Control-Allow-Headers: "customKey1,customKey2, headers, Origin, X-Requested-With, Content-Type, Accept, Authorization"
I have a simple PHP script that I am attempting a cross-domain CORS request:
<?php
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Headers: *");
...
Yet I still get the error:
Request header field X-Requested-With is not allowed by Access-Control-Allow-Headers
Anything I'm missing?
Handling CORS requests properly is a tad more involved. Here is a function that will respond more fully (and properly).
/**
* An example CORS-compliant method. It will allow any GET, POST, or OPTIONS requests from any
* origin.
*
* In a production environment, you probably want to be more restrictive, but this gives you
* the general idea of what is involved. For the nitty-gritty low-down, read:
*
* - https://developer.mozilla.org/en/HTTP_access_control
* - https://fetch.spec.whatwg.org/#http-cors-protocol
*
*/
function cors() {
// Allow from any origin
if (isset($_SERVER['HTTP_ORIGIN'])) {
// Decide if the origin in $_SERVER['HTTP_ORIGIN'] is one
// you want to allow, and if so:
header("Access-Control-Allow-Origin: {$_SERVER['HTTP_ORIGIN']}");
header('Access-Control-Allow-Credentials: true');
header('Access-Control-Max-Age: 86400'); // cache for 1 day
}
// Access-Control headers are received during OPTIONS requests
if ($_SERVER['REQUEST_METHOD'] == 'OPTIONS') {
if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_METHOD']))
// may also be using PUT, PATCH, HEAD etc
header("Access-Control-Allow-Methods: GET, POST, OPTIONS");
if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']))
header("Access-Control-Allow-Headers: {$_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']}");
exit(0);
}
echo "You have CORS!";
}
Security Notes
Check the HTTP_ORIGIN header against a list of approved origins.
If the origin isn't approved, then you should deny the request.
Please read the spec.
TL;DR
When a browser wants to execute a cross-site request it first confirms that this is okay with a "pre-flight" request to the URL. By allowing CORS you are telling the browser that responses from this URL can be shared with other domains.
CORS does not protect your server. CORS attempts to protect your users by telling browsers what the restrictions should be on sharing responses with other domains. Normally this kind of sharing is utterly forbidden, so CORS is a way to poke a hole in the browser's normal security policy. These holes should be as small as possible, so always check the HTTP_ORIGIN against some kind of internal list.
There are some dangers here, especially if the data the URL serves up is normally protected. You are effectively allowing browser content that originated on some other server to read (and possibly manipulate) data on your server.
If you are going to use CORS, please read the protocol carefully (it is quite small) and try to understand what you're doing. A reference URL is given in the code sample for that purpose.
Header security
It has been observed that the HTTP_ORIGIN header is insecure, and that is true. In fact, all HTTP headers are insecure to varying meanings of the term. Unless a header includes a verifiable signature/hmac, or the whole conversation is authenticated via TLS, headers are just "something the browser has told me".
In this case, the browser is saying "an object from domain X wants to get a response from this URL. Is that okay?" The point of CORS is to be able to answer, "yes I'll allow that".
I got the same error, and fixed it with the following PHP in my back-end script:
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: GET, POST');
header("Access-Control-Allow-Headers: X-Requested-With");
Access-Control-Allow-Headers does not allow * as accepted value, see the Mozilla Documentation here.
Instead of the asterisk, you should send the accepted headers (first X-Requested-With as the error says).
Update:
* is now accepted is Access-Control-Allow-Headers.
According to MDN Web Docs 2021:
The value * only counts as a special wildcard value for requests without credentials (requests without HTTP cookies or HTTP authentication information). In requests with credentials, it is treated as the literal header name * without special semantics. Note that the Authorization header can't be wildcarded and always needs to be listed explicitly.
Many description internet-wide don't mention that specifying Access-Control-Allow-Origin is not enough. Here is a complete example that works for me:
<?php
if ($_SERVER['REQUEST_METHOD'] === 'OPTIONS') {
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: POST, GET, DELETE, PUT, PATCH, OPTIONS');
header('Access-Control-Allow-Headers: token, Content-Type');
header('Access-Control-Max-Age: 1728000');
header('Content-Length: 0');
header('Content-Type: text/plain');
die();
}
header('Access-Control-Allow-Origin: *');
header('Content-Type: application/json');
$ret = [
'result' => 'OK',
];
print json_encode($ret);
I've simply managed to get dropzone and other plugin to work with this fix (angularjs + php backend)
header('Access-Control-Allow-Origin: *');
header("Access-Control-Allow-Credentials: true");
header('Access-Control-Allow-Methods: GET, PUT, POST, DELETE, OPTIONS');
header('Access-Control-Max-Age: 1000');
header('Access-Control-Allow-Headers: Origin, Content-Type, X-Auth-Token , Authorization');
add this in your upload.php or where you would send your request (for example if you have upload.html and you need to attach the files to upload.php, then copy and paste these 4 lines).
Also if you're using CORS plugins/addons in chrome/mozilla be sure to toggle them more than one time,in order for CORS to be enabled
If you want to create a CORS service from PHP, you can use this code as the first step in your file that handles the requests:
// Allow from any origin
if(isset($_SERVER["HTTP_ORIGIN"]))
{
// You can decide if the origin in $_SERVER['HTTP_ORIGIN'] is something you want to allow, or as we do here, just allow all
header("Access-Control-Allow-Origin: {$_SERVER['HTTP_ORIGIN']}");
}
else
{
//No HTTP_ORIGIN set, so we allow any. You can disallow if needed here
header("Access-Control-Allow-Origin: *");
}
header("Access-Control-Allow-Credentials: true");
header("Access-Control-Max-Age: 600"); // cache for 10 minutes
if($_SERVER["REQUEST_METHOD"] == "OPTIONS")
{
if (isset($_SERVER["HTTP_ACCESS_CONTROL_REQUEST_METHOD"]))
header("Access-Control-Allow-Methods: POST, GET, OPTIONS, DELETE, PUT"); //Make sure you remove those you do not want to support
if (isset($_SERVER["HTTP_ACCESS_CONTROL_REQUEST_HEADERS"]))
header("Access-Control-Allow-Headers: {$_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']}");
//Just exit with 200 OK with the above headers for OPTIONS method
exit(0);
}
//From here, handle the request as it is ok
CORS can become a headache, if we do not correctly understand its functioning. I use them in PHP and they work without problems. reference here
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Credentials: true");
header("Access-Control-Max-Age: 1000");
header("Access-Control-Allow-Headers: X-Requested-With, Content-Type, Origin, Cache-Control, Pragma, Authorization, Accept, Accept-Encoding");
header("Access-Control-Allow-Methods: PUT, POST, GET, OPTIONS, DELETE");
This much code works down for me when using angular 4 as the client side and PHP as the server side.
header("Access-Control-Allow-Origin: *");
this should work
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Headers: X-Requested-With, Content-Type, Origin, Cache-Control, Pragma, Authorization, Accept, Accept-Encoding");
I used these 5 headers and after that solved the cors error(backend: PHP, Frontend: VUE JS)
header('Access-Control-Allow-Origin: *');
header('Access-Control-Allow-Methods: GET, PUT, POST, DELETE, OPTIONS, post, get');
header("Access-Control-Max-Age", "3600");
header('Access-Control-Allow-Headers: Origin, Content-Type, X-Auth-Token');
header("Access-Control-Allow-Credentials", "true");
add this code in .htaccess
add custom authentication key's in header like app_key,auth_key..etc
Header set Access-Control-Allow-Origin "*"
Header set Access-Control-Allow-Headers: "customKey1,customKey2, headers, Origin, X-Requested-With, Content-Type, Accept, Authorization"