n8n-io/n8n · error · Error

Webhook URL cannot target private/internal IP addresses

Error message

Webhook URL cannot target private/internal IP addresses

What it means

Thrown from `validateWebhookUrl` when the hostname itself is a literal private/loopback/link-local IPv4 or IPv6 address matched by `isPrivateIp` (e.g. `10.x`, `172.16-31.x`, `192.168.x`, `169.254.x`, `0.0.0.0`, `fc/fd`, `fe80:`, `::1`). This is the literal-IP branch of SSRF protection — it blocks direct targeting of internal address space before any DNS lookup. The hostname has already passed the localhost/private-name checks above.

Source

Thrown at packages/@n8n/ai-workflow-builder.ee/evaluations/cli/webhook.ts:130

	const url = new URL(webhookUrl);

	if (url.protocol !== 'https:') {
		throw new Error(`Webhook URL must use HTTPS. Got: ${url.protocol}`);
	}

	const hostname = url.hostname.toLowerCase();

	if (
		hostname === 'localhost' ||
		hostname === '127.0.0.1' ||
		hostname === '::1' ||
		hostname === '[::1]'
	) {
		throw new Error('Webhook URL cannot target localhost');
	}

	if (isPrivateIp(hostname)) {
		throw new Error('Webhook URL cannot target private/internal IP addresses');
	}

	const blockedHostnames = ['internal', 'intranet', 'corp', 'private', 'local'];
	for (const blocked of blockedHostnames) {
		if (hostname === blocked || hostname.endsWith(`.${blocked}`)) {
			throw new Error(`Webhook URL cannot target internal hostname: ${hostname}`);
		}
	}
}

/**
 * Validate webhook URL with DNS resolution for comprehensive SSRF protection.
 * Resolves the hostname and validates that resolved IPs are not private/internal.
 */
export async function validateWebhookUrlWithDns(webhookUrl: string): Promise<void> {
	validateWebhookUrl(webhookUrl);

	const url = new URL(webhookUrl);

View on GitHub (pinned to 5ac6606e81)

Solutions

1. Use the public hostname of the service rather than an RFC1918 IP literal.
2. Route through a public ingress/proxy that itself reaches the internal host.
3. If delivery to an internal host is genuinely required, send the webhook from outside this SSRF-restricted code path (e.g. your own service consuming eval output from stdout/a file).

Example fix

// before
validateWebhookUrl('https://10.0.0.5/hook');
// after
validateWebhookUrl('https://ingress.example.com/hook');

// mirror the isPrivateIp predicate at the call site
function isPrivateIp(ip: string): boolean {
  return [/^127\./, /^10\./, /^172\.(1[6-9]|2\d|3[01])\./, /^192\.168\./, /^169\.254\./, /^0\.0\.0\.0$/].some((p) => p.test(ip))
    || /^::1$/.test(ip) || ip.startsWith('fe80:') || ip.startsWith('fc') || ip.startsWith('fd');
}
const h = new URL(webhookUrl).hostname.toLowerCase();
if (isPrivateIp(h)) throw new Error(`webhook host ${h} is a private IP literal`);

When it happens

Trigger: `--webhook-url https://10.0.0.5/hook`, `https://192.168.1.10/hook`, `https://172.20.0.3/hook`, or IPv6 unique-local forms. URL is HTTPS, hostname is not `localhost`, but matches a private CIDR pattern.

Common situations: Targeting an internal service mesh address, a Docker bridge IP, or a corp-network host by IP. Sometimes the result of resolving a hostname ahead of time and pasting the IP into config.

Related errors

• Webhook URL must use HTTPS. Got: ${url.protocol}
• Webhook URL cannot target localhost
• Webhook URL cannot target internal hostname: ${hostname}
• Webhook URL hostname resolves to a private/internal IP addre
• Invalid skill at ${sourceDirectory}: ${errors.join('; ')}

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/6cd02db42f5545ed. Report an issue: GitHub.