Avoid unsafe CORS headers

Metadata

ID: csharp-security/unsafe-cors

Language: C#

Severity: Warning

Category: Security

Description

Your CORS policy should never allow all other resources. Instead, you must have a restrictive CORS policy to ensure your application only connects and exchanges data with trusted sources.

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Non-Compliant Code Examples

class MyClass {
    public static void payloadDecode()
    {
        response.Headers.Add("Access-Control-Allow-Origin", "*");
        response.Headers.Add(HeaderNames.AccessControlAllowOrigin, "*");
        response.AppendHeader(HeaderNames.AccessControlAllowOrigin, "*");
    }
}

Compliant Code Examples

class MyClass {
    public static void payloadDecode()
    {
        response.Headers.Add("Access-Control-Allow-Origin", "https://domain.tld");
        response.Headers.Add(HeaderNames.AccessControlAllowOrigin, "https://domain.tld");
        response.AppendHeader(HeaderNames.AccessControlAllowOrigin, "https://domain.tld");
    }
}