Why is Access-Control-Expose-Headers needed?

CORS is implemented in such a way that it does not break assumptions made in the pre-CORS, same-origin-only world. In the pre-CORS world, a client could trigger a cross-origin request (for example, via a script tag), but it could not read the response headers. In order to ensure that CORS doesn’t break this assumption, the … Read more

Cross-origin request in a content script is blocked by CORB despite the correct CORS headers

Based on the examples in “Changes to Cross-Origin Requests in Chrome Extension Content Scripts”, I replaced all invocations of fetch with a new method fetchResource, that has a similar API, but delegates the fetch call to the background page: // contentScript.js function fetchResource(input, init) { return new Promise((resolve, reject) => { chrome.runtime.sendMessage({input, init}, messageResponse => … Read more

Does Wikipedia API support CORS or only JSONP available?

To make JavaScript Fetch/XHR requests to Wikipedia, add origin=* to the URL query params. So the base of the URL in the question should be like this: https://en.wikipedia.org/w/api.php?origin=*&action=query… See the CORS-related docs for the Wikipedia backend: For anonymous requests, origin query string parameter can be set to * which will allow requests from anywhere. 2016-05-09 … Read more

AngularJS + Django Rest Framework + CORS ( CSRF Cookie not showing up in client )

AngularJS Single Page Web Application on Sub-domain A, talking to a Django JSON (REST) API on Sub-domain B using CORS and CSRF protection Since I’m currently working on a similar setup and was battling to get CORS to work properly in combination with CSRF protection, I wanted to share my own learnings here. Setup – … Read more

HTTP OPTIONS request on Azure Websites fails due to CORS

I decided to post a complete solution to this problem since the answers already provided (while technically correct) don’t work in this particular case for me. The trick was to do the following: 1. Add <customHeaders> in <httpProtocol> in web.config Like @hcoat also suggested above, adding system.webServer.httpProtocol.customHeaders was the first step to resolve the issue … Read more

NextJs CORS issue

I found a solution here: Basically, I just need to add a next.config.js file in the root directory and add the following: // next.config.js module.exports = { async rewrites() { return [ { source: ‘/api/:path*’, destination: ‘https://api.example.com/:path*’, }, ] }, };

Asp.Net WebApi2 Enable CORS not working with AspNet.WebApi.Cors 5.2.3

I’ve created a pared-down demo project for you. Source: https://github.com/bigfont/webapi-cors Api Link: https://cors-webapi.azurewebsites.net/api/values You can try the above API Link from your local Fiddler to see the headers. Here is an explanation. Global.ascx All this does is call the WebApiConfig. It’s nothing but code organization. public class WebApiApplication : System.Web.HttpApplication { protected void Application_Start() { … Read more

CORS error on request to localhost dev server from remote site

Original Answer I finally found the answer, in this RFC about CORS-RFC1918 from a Chrome-team member. To sum it up, Chrome has implemented CORS-RFC1918, which prevents public network resources from requesting private-network resources – unless the public-network resource is secure (HTTPS) and the private-network resource provides appropriate (yet-undefined) CORS headers. There’s also a Chrome flag … Read more