diff --git a/src/__tests__/network.test.ts b/src/__tests__/network.test.ts
index adfbd5e..6dceac4 100644
--- a/src/__tests__/network.test.ts
+++ b/src/__tests__/network.test.ts
@@ -34,6 +34,19 @@ describe('validateUrl', () => {
     expect(validateUrl('http://127.0.0.1:8000', { allowInsecureLocalhost: true }).hostname).toBe(
       '127.0.0.1',
     );
+    // Full 127.0.0.0/8 range — not just .1
+    expect(validateUrl('http://127.0.0.2:8000', { allowInsecureLocalhost: true }).hostname).toBe(
+      '127.0.0.2',
+    );
+    // IPv6 loopback — WHATWG URL parser always returns the bracketed form
+    expect(validateUrl('http://[::1]:8000', { allowInsecureLocalhost: true }).hostname).toBe(
+      '[::1]',
+    );
+  });
+
+  it('rejects http on loopback addresses unless opted in', () => {
+    expect(() => validateUrl('http://127.0.0.2:8000')).toThrow(VeroError);
+    expect(() => validateUrl('http://[::1]:8000')).toThrow(VeroError);
   });
 
   it('does not permit http on a remote host even when localhost is opted in', () => {
diff --git a/src/network/index.ts b/src/network/index.ts
index 1a2028a..a737309 100644
--- a/src/network/index.ts
+++ b/src/network/index.ts
@@ -38,7 +38,20 @@ export const MAINNET: NetworkConfig = {
   network: 'mainnet',
 };
 
-const LOCAL_HOSTS = new Set(['localhost', '127.0.0.1', '[::1]', '::1']);
+/**
+ * Returns true for hostnames that are loopback addresses:
+ * - "localhost"
+ * - IPv4 127.0.0.0/8 (e.g. 127.0.0.1, 127.0.0.2, …)
+ * - IPv6 [::1] (as returned by the WHATWG URL parser — always bracketed)
+ *
+ * Note: the WHATWG URL parser always brackets IPv6 addresses, so bare "::1"
+ * can never appear in `parsed.hostname` and is intentionally excluded here.
+ */
+function isLoopback(hostname: string): boolean {
+  if (hostname === 'localhost' || hostname === '[::1]') return true;
+  // Match 127.x.x.x (the full 127.0.0.0/8 loopback range)
+  return /^127\.\d{1,3}\.\d{1,3}\.\d{1,3}$/.test(hostname);
+}
 
 export interface ValidateUrlOptions {
   /**
@@ -69,7 +82,7 @@ export function validateUrl(url: string, opts: ValidateUrlOptions = {}): URL {
   if (parsed.protocol === 'https:') return parsed;
 
   if (parsed.protocol === 'http:') {
-    const isLocal = LOCAL_HOSTS.has(parsed.hostname);
+    const isLocal = isLoopback(parsed.hostname);
     if (isLocal && opts.allowInsecureLocalhost) return parsed;
 
     throw new VeroError(