Glossary · Security
Cross-Origin Resource Sharing
A browser security mechanism that controls which origins may make requests to an API or resource from client side JavaScript.
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Cross-Origin Resource Sharing (CORS) is the mechanism by which servers declare which other origins (domain + scheme + port combinations) may make cross-origin requests from a browser. Without CORS restrictions, a malicious website could use a logged in user's browser to make API calls to your server. The browser enforces CORS via preflight OPTIONS requests and response headers (Access-Control-Allow-Origin). A misconfigured CORS policy that sets Access-Control-Allow-Origin to * or reflects the request origin without validation effectively disables the protection.
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