feat: Env to disable webhook response iframe sandboxing (#17851)

Author: michael-radency

packages/@n8n/config/src/configs/security.config.ts

@@ -38,4 +38,8 @@ export class SecurityConfig {
 	 */
 	@Env('N8N_CONTENT_SECURITY_POLICY_REPORT_ONLY')
 	contentSecurityPolicyReportOnly: boolean = false;
+
+	/** Whether to disable iframe sandboxing for webhooks */
+	@Env('N8N_INSECURE_DISABLE_WEBHOOK_IFRAME_SANDBOX')
+	disableIframeSandboxing: boolean = false;
 }

packages/@n8n/config/test/config.test.ts

@@ -303,6 +303,7 @@ describe('GlobalConfig', () => {
 			daysAbandonedWorkflow: 90,
 			contentSecurityPolicy: '{}',
 			contentSecurityPolicyReportOnly: false,
+			disableIframeSandboxing: false,
 		},
 		executions: {
 			pruneData: true,

packages/cli/src/webhooks/webhook-request-handler.ts

@@ -151,7 +151,7 @@ class WebhookRequestHandler {
 		} else {
 			const needsSandbox = contentType && isHtmlRenderedContentType(contentType);
 			if (needsSandbox) {
-				res.send(sandboxHtmlResponse(JSON.stringify(body)));
+				res.send(sandboxHtmlResponse(body));
 			} else {
 				res.json(body);
 			}

packages/core/src/__tests__/html-sandbox.test.ts

@@ -1,3 +1,6 @@
+import type { SecurityConfig } from '@n8n/config';
+import { Container } from '@n8n/di';
+import { mock } from 'jest-mock-extended';
 import { Readable } from 'stream';
 
 import {
@@ -18,7 +21,16 @@ async function consumeStreamToString(stream: NodeJS.ReadableStream): Promise<str
 	});
 }
 
+const securityConfig = mock<SecurityConfig>();
+
 describe('sandboxHtmlResponse', () => {
+	beforeAll(() => {
+		securityConfig.disableIframeSandboxing = false;
+		jest.spyOn(Container, 'get').mockReturnValue(securityConfig);
+	});
+	afterAll(() => {
+		jest.restoreAllMocks();
+	});
 	it('should replace ampersands and double quotes in HTML', () => {
 		const html = '<div class="test">Content & more</div>';
 		expect(sandboxHtmlResponse(html)).toMatchSnapshot();
@@ -305,6 +317,13 @@ describe('createHtmlSandboxTransformStream', () => {
 });
 
 describe('sandboxHtmlResponse > not string types', () => {
+	beforeAll(() => {
+		securityConfig.disableIframeSandboxing = false;
+		jest.spyOn(Container, 'get').mockReturnValue(securityConfig);
+	});
+	afterAll(() => {
+		jest.restoreAllMocks();
+	});
 	it('should not throw if data is number', () => {
 		const data = 123;
 		expect(() => sandboxHtmlResponse(data)).not.toThrow();
@@ -320,3 +339,37 @@ describe('sandboxHtmlResponse > not string types', () => {
 		expect(() => sandboxHtmlResponse(data)).not.toThrow();
 	});
 });
+
+describe('sandboxHtmlResponse > sandboxing disabled', () => {
+	beforeAll(() => {
+		securityConfig.disableIframeSandboxing = true;
+		jest.spyOn(Container, 'get').mockReturnValue(securityConfig);
+	});
+	afterAll(() => {
+		jest.restoreAllMocks();
+	});
+	it('should return unchanged number data', () => {
+		const data = 123;
+		expect(sandboxHtmlResponse(data)).toEqual(data);
+	});
+
+	it('should return unchanged object data', () => {
+		const data = {};
+		expect(sandboxHtmlResponse(data)).toEqual(data);
+	});
+
+	it('should return unchanged boolean data', () => {
+		const data = true;
+		expect(sandboxHtmlResponse(data)).toEqual(data);
+	});
+
+	it('should return unchanged text data', () => {
+		const data = 'string data';
+		expect(sandboxHtmlResponse(data)).toEqual(data);
+	});
+
+	it('should return unchanged html data', () => {
+		const data = '<p>html data</p>';
+		expect(sandboxHtmlResponse(data)).toEqual(data);
+	});
+});

packages/core/src/html-sandbox.ts

@@ -1,7 +1,13 @@
+import { SecurityConfig } from '@n8n/config';
+import { Container } from '@n8n/di';
 import { JSDOM } from 'jsdom';
 import type { TransformCallback } from 'stream';
 import { Transform } from 'stream';
 
+export const isIframeSandboxDisabled = () => {
+	return Container.get(SecurityConfig).disableIframeSandboxing;
+};
+
 /**
  * Checks if the given string contains HTML.
  */
@@ -20,22 +26,23 @@ export const hasHtml = (str: string) => {
  * Sandboxes the HTML response to prevent possible exploitation, if the data has HTML.
  * If the data does not have HTML, it will be returned as is.
  * Otherwise, it embeds the response in an iframe to make sure the HTML has a different origin.
+ * Env var `N8N_INSECURE_DISABLE_WEBHOOK_IFRAME_SANDBOX` can be used, in this case sandboxing is disabled.
  *
  * @param data - The data to sandbox.
  * @param forceSandbox - Whether to force sandboxing even if the data does not contain HTML.
  * @returns The sandboxed HTML response.
  */
 export const sandboxHtmlResponse = <T>(data: T, forceSandbox = false) => {
+	if (isIframeSandboxDisabled()) return data;
+
 	let text;
 	if (typeof data !== 'string') {
 		text = JSON.stringify(data);
 	} else {
 		text = data;
 	}
 
-	if (!forceSandbox && !hasHtml(text)) {
-		return text;
-	}
+	if (!forceSandbox && !hasHtml(text)) return text;
 
 	// Escape & and " as mentioned in the spec:
 	// https://html.spec.whatwg.org/multipage/iframe-embed-object.html#the-iframe-element

packages/nodes-base/nodes/RespondToWebhook/utils/binary.ts

@@ -1,4 +1,4 @@
-import { isHtmlRenderedContentType, sandboxHtmlResponse } from 'n8n-core';
+import { isHtmlRenderedContentType, sandboxHtmlResponse, isIframeSandboxDisabled } from 'n8n-core';
 import type { IBinaryData, IDataObject, IN8nHttpResponse } from 'n8n-workflow';
 import { BINARY_ENCODING } from 'n8n-workflow';
 import type { Readable } from 'stream';
@@ -16,9 +16,15 @@ const setContentLength = (responseBody: IN8nHttpResponse | Readable, headers: ID
  */
 export const getBinaryResponse = (binaryData: IBinaryData, headers: IDataObject) => {
 	const contentType = headers['content-type'] as string;
-	const shouldSandboxResponseData =
-		isHtmlRenderedContentType(binaryData.mimeType) ||
-		(contentType && isHtmlRenderedContentType(contentType));
+
+	let shouldSandboxResponseData;
+	if (isIframeSandboxDisabled()) {
+		shouldSandboxResponseData = false;
+	} else {
+		shouldSandboxResponseData =
+			isHtmlRenderedContentType(binaryData.mimeType) ||
+			(contentType && isHtmlRenderedContentType(contentType));
+	}
 
 	let responseBody: IN8nHttpResponse | Readable;