fix: checkOrigin headers check (#12632)

* Merge commit from fork

* fix: enforce check origin logic

* address feedback

* --amend

Author: ematipico

.changeset/swift-pandas-serve.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes an issue where the `checkOrigin` feature wasn't correctly checking the `content-type` header

packages/astro/src/core/app/middlewares.ts

@@ -21,22 +21,43 @@ const FORM_CONTENT_TYPES = [
 export function createOriginCheckMiddleware(): MiddlewareHandler {
 	return defineMiddleware((context, next) => {
 		const { request, url } = context;
-		const contentType = request.headers.get('content-type');
-		if (contentType) {
-			if (FORM_CONTENT_TYPES.includes(contentType.toLowerCase())) {
-				const forbidden =
-					(request.method === 'POST' ||
-						request.method === 'PUT' ||
-						request.method === 'PATCH' ||
-						request.method === 'DELETE') &&
-					request.headers.get('origin') !== url.origin;
-				if (forbidden) {
-					return new Response(`Cross-site ${request.method} form submissions are forbidden`, {
-						status: 403,
-					});
-				}
+		if (request.method === "GET") {
+			return next();
+		}
+		const sameOrigin =
+			(request.method === 'POST' ||
+				request.method === 'PUT' ||
+				request.method === 'PATCH' ||
+				request.method === 'DELETE') &&
+			request.headers.get('origin') === url.origin;
+		
+		const hasContentType = request.headers.has('content-type')
+		if (hasContentType) {
+			const formLikeHeader = hasFormLikeHeader(request.headers.get('content-type'));
+			if (formLikeHeader && !sameOrigin) {
+				return new Response(`Cross-site ${request.method} form submissions are forbidden`, {
+					status: 403,
+				});
+			}
+		} else {
+			if (!sameOrigin) {
+				return new Response(`Cross-site ${request.method} form submissions are forbidden`, {
+					status: 403,
+				});
 			}
 		}
-		return next();
+
+		return next()
 	});
 }
+
+function hasFormLikeHeader(contentType: string | null): boolean {
+	if (contentType) {
+		for (const FORM_CONTENT_TYPE of FORM_CONTENT_TYPES) {
+			if (contentType.toLowerCase().includes(FORM_CONTENT_TYPE)) {
+				return true;
+			}
+		}
+	}
+	return false;
+}

packages/astro/test/csrf-protection.test.js

@@ -46,6 +46,22 @@ describe('CSRF origin check', () => {
 		});
 		response = await app.render(request);
 		assert.equal(response.status, 403);
+
+		request = new Request('http://example.com/api/', {
+			headers: { origin: 'http://loreum.com', 'content-type': 'application/x-www-form-urlencoded; some-other-value' },
+			method: 'POST',
+		});
+		response = await app.render(request);
+		assert.equal(response.status, 403);
+
+		request = new Request('http://example.com/api/', {
+			headers: { origin: 'http://loreum.com', },
+			method: 'POST',
+			credentials: 'include',
+			body: new Blob(["a=b"],{})
+		});
+		response = await app.render(request);
+		assert.equal(response.status, 403);
 	});
 
 	it("return 403 when the origin doesn't match and calling a PUT", async () => {