diff --git a/.env.example b/.env.example
index a4ba843..9cdc42b 100644
--- a/.env.example
+++ b/.env.example
@@ -23,10 +23,9 @@ JWT_SECRET=super_secret_jwt_key_123
 # --- CAPTCHA / Bot Protection (Optional) ---
 # Create keys in Cloudflare Turnstile and set both values in production.
 # When TURNSTILE_SECRET is empty, backend CAPTCHA enforcement is disabled.
+TURNSTILE_SITE_KEY=
 TURNSTILE_SECRET=
 
 # --- Frontend Configuration (Optional) ---
 # If you need to override the API URL for the frontend
 # VITE_API_URL=/api
-# Cloudflare Turnstile site key shown on the login page
-VITE_TURNSTILE_SITE_KEY=
diff --git a/Dockerfile b/Dockerfile
index 4bd6b7a..4e2b46a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,8 +1,6 @@
 # Build stage
 FROM node:20-alpine AS build
 WORKDIR /app
-ARG VITE_TURNSTILE_SITE_KEY
-ENV VITE_TURNSTILE_SITE_KEY=$VITE_TURNSTILE_SITE_KEY
 COPY package*.json ./
 RUN npm install
 COPY . .
diff --git a/README.md b/README.md
index 87cbfea..443f05f 100644
--- a/README.md
+++ b/README.md
@@ -112,16 +112,13 @@ N8N_WHATSAPP_TRIGGER_URL
 ADMIN_EMAIL
 ADMIN_PASSWORD
 JWT_SECRET
+TURNSTILE_SITE_KEY
 TURNSTILE_SECRET
-VITE_TURNSTILE_SITE_KEY
 ```
 
-`TURNSTILE_SECRET` enables backend CAPTCHA enforcement on `/api/login`.
-Set `VITE_TURNSTILE_SITE_KEY` at frontend build time to show Cloudflare Turnstile
-on the login page.
-
-If `TURNSTILE_SECRET` is set but the login page does not show the verification
-widget, rebuild the frontend image with `VITE_TURNSTILE_SITE_KEY` available.
+`TURNSTILE_SECRET` enables backend CAPTCHA enforcement on `/api/login`. Set
+`TURNSTILE_SITE_KEY` with Cloudflare's public site key so the login page can load
+the verification widget at runtime.
 
 ## Validation
 
diff --git a/backend/config.js b/backend/config.js
index 4d86a60..7086dc1 100644
--- a/backend/config.js
+++ b/backend/config.js
@@ -8,5 +8,6 @@ module.exports = {
     JWT_SECRET: process.env.JWT_SECRET || 'super_secret_jwt_key_123',
     DATABASE_URL: process.env.DATABASE_URL || 'postgres://graphuser:graphpassword@localhost:5432/graphdb',
     N8N_WHATSAPP_TRIGGER_URL: process.env.N8N_WHATSAPP_TRIGGER_URL || 'http://localhost:5678/webhook/whatsapp',
+    TURNSTILE_SITE_KEY: process.env.TURNSTILE_SITE_KEY || process.env.VITE_TURNSTILE_SITE_KEY || '',
     TURNSTILE_SECRET: process.env.TURNSTILE_SECRET || process.env.TURNSTILE_SECRET_KEY || ''
 };
diff --git a/backend/routes/authRoutes.js b/backend/routes/authRoutes.js
index 90cc000..95f5093 100644
--- a/backend/routes/authRoutes.js
+++ b/backend/routes/authRoutes.js
@@ -1,6 +1,6 @@
 const express = require('express');
 const { login } = require('../auth');
-const { TURNSTILE_SECRET } = require('../config');
+const { TURNSTILE_SECRET, TURNSTILE_SITE_KEY } = require('../config');
 
 const router = express.Router();
 const TURNSTILE_VERIFY_URL = 'https://challenges.cloudflare.com/turnstile/v0/siteverify';
@@ -34,6 +34,13 @@ const verifyCaptcha = async (captchaToken, remoteIp) => {
     }
 };
 
+router.get('/login/config', (req, res) => {
+    res.json({
+        captchaRequired: Boolean(TURNSTILE_SECRET),
+        turnstileSiteKey: TURNSTILE_SITE_KEY
+    });
+});
+
 router.post('/login', async (req, res, next) => {
     const { email, password, captchaToken } = req.body;
 
diff --git a/docker-compose.yml b/docker-compose.yml
index ec56bdc..297f917 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -27,6 +27,7 @@ services:
       - ADMIN_PASSWORD=${ADMIN_PASSWORD:-admin123}
       - JWT_SECRET=${JWT_SECRET:-super_secret_jwt_key_123}
       - N8N_WHATSAPP_TRIGGER_URL=${N8N_WHATSAPP_TRIGGER_URL:-http://localhost:5678/webhook/whatsapp}
+      - TURNSTILE_SITE_KEY=${TURNSTILE_SITE_KEY:-${VITE_TURNSTILE_SITE_KEY:-}}
       - TURNSTILE_SECRET=${TURNSTILE_SECRET:-${TURNSTILE_SECRET_KEY:-}}
     depends_on:
       - db
@@ -35,8 +36,6 @@ services:
   frontend:
     build:
       context: .
-      args:
-        VITE_TURNSTILE_SITE_KEY: ${VITE_TURNSTILE_SITE_KEY:-}
     image: gitea.blyzer.com.br/blyzer/graphs-frontend:latest
     container_name: graph_frontend
     ports:
diff --git a/src/dataService.ts b/src/dataService.ts
index d68b3c9..c189342 100644
--- a/src/dataService.ts
+++ b/src/dataService.ts
@@ -55,8 +55,19 @@ const buildDateRangeParams = (dateRange: DateRange) => new URLSearchParams({
     end: formatDateParam(dateRange.end)
 });
 
+export type LoginConfig = {
+  captchaRequired: boolean;
+  turnstileSiteKey: string;
+};
+
 export type LoginResult = 'success' | 'invalid_credentials' | 'captcha_failed' | 'server_error';
 
+export const getLoginConfig = async (): Promise<LoginConfig> => {
+  const response = await fetch(`${API_URL}/login/config`, { cache: 'no-store' });
+  if (!response.ok) throw new Error('Failed to load login config');
+  return response.json() as Promise<LoginConfig>;
+};
+
 export const login = async (email: string, password: string, captchaToken?: string): Promise<LoginResult> => {
   try {
     const response = await fetch(`${API_URL}/login`, {
diff --git a/src/pages/Login.tsx b/src/pages/Login.tsx
index 1cba751..4ba48c6 100644
--- a/src/pages/Login.tsx
+++ b/src/pages/Login.tsx
@@ -1,7 +1,7 @@
 import { useEffect, useRef, useState } from 'react';
 import { useNavigate } from 'react-router-dom';
 import { Lock } from 'lucide-react';
-import { login } from '../dataService';
+import { getLoginConfig, login } from '../dataService';
 
 declare global {
   interface Window {
@@ -21,8 +21,8 @@ declare global {
   }
 }
 
-const turnstileSiteKey = import.meta.env.VITE_TURNSTILE_SITE_KEY;
 const turnstileScriptId = 'turnstile-api-script';
+const securityConfigLoadMessage = 'Não foi possível carregar as configurações de segurança. Atualize a página e tente novamente.';
 const securityUnavailableMessage = 'Não foi possível carregar a verificação de segurança. Atualize a página e tente novamente.';
 const securityConfigurationMessage = 'Verificação de segurança indisponível. Entre em contato com o administrador.';
 const securityRequiredMessage = 'Conclua a verificação de segurança para continuar.';
@@ -34,11 +34,47 @@ const Login = () => {
   const [captchaToken, setCaptchaToken] = useState('');
   const [error, setError] = useState('');
   const [isLoading, setIsLoading] = useState(false);
-  const [captchaReady, setCaptchaReady] = useState(!turnstileSiteKey);
+  const [isConfigLoading, setIsConfigLoading] = useState(true);
+  const [turnstileSiteKey, setTurnstileSiteKey] = useState('');
+  const [captchaRequired, setCaptchaRequired] = useState(false);
+  const [captchaReady, setCaptchaReady] = useState(true);
   const captchaContainerRef = useRef<HTMLDivElement | null>(null);
   const captchaWidgetIdRef = useRef<string | null>(null);
   const navigate = useNavigate();
-  const captchaEnabled = Boolean(turnstileSiteKey);
+  const captchaEnabled = Boolean(captchaRequired && turnstileSiteKey);
+  const securityMisconfigured = captchaRequired && !turnstileSiteKey;
+
+  useEffect(() => {
+    let isMounted = true;
+
+    const loadLoginConfig = async () => {
+      try {
+        const config = await getLoginConfig();
+        if (!isMounted) return;
+
+        setCaptchaRequired(config.captchaRequired);
+        setTurnstileSiteKey(config.turnstileSiteKey);
+        setCaptchaReady(!config.captchaRequired);
+        if (config.captchaRequired && !config.turnstileSiteKey) {
+          setError(securityConfigurationMessage);
+        }
+      } catch {
+        if (!isMounted) return;
+        setCaptchaReady(false);
+        setError(securityConfigLoadMessage);
+      } finally {
+        if (isMounted) {
+          setIsConfigLoading(false);
+        }
+      }
+    };
+
+    void loadLoginConfig();
+
+    return () => {
+      isMounted = false;
+    };
+  }, []);
 
   useEffect(() => {
     if (!turnstileSiteKey || !captchaContainerRef.current || captchaWidgetIdRef.current) return;
@@ -92,10 +128,15 @@ const Login = () => {
     document.head.appendChild(script);
 
     return () => script.removeEventListener('load', renderCaptcha);
-  }, [captchaEnabled]);
+  }, [turnstileSiteKey]);
 
   const handleLogin = async (e: React.FormEvent) => {
     e.preventDefault();
+    if (securityMisconfigured) {
+      setError(securityConfigurationMessage);
+      return;
+    }
+
     if (captchaEnabled && !captchaToken) {
       setError(securityRequiredMessage);
       return;
@@ -173,10 +214,10 @@ const Login = () => {
             />
           </div>
 
-          {captchaEnabled && (
+          {(captchaEnabled || securityMisconfigured) && (
             <div className="min-h-[70px] rounded-xl border border-dark-border bg-dark-input/60 p-3">
-              <div ref={captchaContainerRef} className="flex justify-center" />
-              {!captchaReady && (
+              {captchaEnabled && <div ref={captchaContainerRef} className="flex justify-center" />}
+              {(securityMisconfigured || !captchaReady) && (
                 <p className="mt-2 text-center text-xs font-medium text-red-400">Verificação de segurança indisponível.</p>
               )}
             </div>
@@ -186,10 +227,10 @@ const Login = () => {
 
           <button
             type="submit"
-            disabled={isLoading || !captchaReady || (captchaEnabled && !captchaToken)}
+            disabled={isLoading || isConfigLoading || securityMisconfigured || !captchaReady || (captchaEnabled && !captchaToken)}
             className="w-full bg-brand-primary hover:bg-opacity-90 hover:scale-[1.02] active:scale-[0.98] text-zinc-900 font-bold py-3 rounded-xl transition-all duration-200 disabled:opacity-50 disabled:hover:scale-100 disabled:active:scale-100 mt-4 cursor-pointer"
           >
-            {isLoading ? 'Entrando...' : 'Entrar'}
+            {isLoading || isConfigLoading ? 'Entrando...' : 'Entrar'}
           </button>
         </form>
       </div>
diff --git a/src/vite-env.d.ts b/src/vite-env.d.ts
index 176f969..c57d674 100644
--- a/src/vite-env.d.ts
+++ b/src/vite-env.d.ts
@@ -2,7 +2,6 @@
 
 interface ImportMetaEnv {
   readonly VITE_API_URL?: string;
-  readonly VITE_TURNSTILE_SITE_KEY?: string;
 }
 
 interface ImportMeta {