Forbidden Error: Invalid CSRF Token
The “Forbidden Error: Invalid CSRF Token” occurs when a Cross-Site Request Forgery (CSRF) token sent with a request is deemed invalid or missing.
Explanation:
CSRF is an attack that tricks the victim into submitting a malicious request. To prevent this, web applications use CSRF tokens. These tokens are unique per session and are included with every form submission or AJAX request. When a request is made, the server checks if the CSRF token matches the one expected for that particular session.
If the CSRF token is missing or does not match, the server returns a “Forbidden Error” and rejects the request for security reasons.
Examples:
Example 1: HTML Form Submission
Consider an HTML form that submits user data:
<form method="POST" action="/submit">
<input type="hidden" name="csrf_token" value="abcdef123456">
<!-- Other form fields -->
</form>
In this example, the form includes a hidden field named “csrf_token” with a value of “abcdef123456”. When the form is submitted, the server expects the received token to match the one associated with the session.
Example 2: AJAX Request
When making AJAX requests, the CSRF token needs to be included in the request headers or payload. Here’s an example using JavaScript:
const csrfToken = "abcdef123456";
const requestData = {
// Other request data
"csrf_token": csrfToken
};
fetch("/api/endpoint", {
method: "POST",
headers: {
"Content-Type": "application/json",
"X-CSRF-Token": csrfToken
},
body: JSON.stringify(requestData)
}).then(response => {
// Handle response
}).catch(error => {
// Handle error
});
In this example, the CSRF token “abcdef123456” is included in the request headers with the key “X-CSRF-Token”. The server validates this token against the session token to ensure the request is not forged.
Solution:
To resolve the “Forbidden Error: Invalid CSRF Token” issue, you can take the following steps:
- Ensure the CSRF token is included with the request, either as a hidden field in HTML forms or in the request headers/payloa
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