diff --git a/index.js b/index.js
index f073c89..ad8531e 100644
--- a/index.js
+++ b/index.js
@@ -2,7 +2,7 @@ const path = require("path");
 const express = require("express");
 const dotenv = require("dotenv");
 const morgan = require("morgan");
-// const mongoSanitize = require("express-mongo-sanitize");
+const mongoSanitize = require("express-mongo-sanitize");
 const helmet = require("helmet");
 // const xssClean = require("xss-clean");
 const expressRateLimit = require("express-rate-limit");
@@ -85,8 +85,13 @@ if (process.env.NODE_ENV === "development") {
 //File Uploading *******************************************************
 app.use(fileUpload());
 
-// Sanitize Data *******************************************************
-// app.use(mongoSanitize());
+// Sanitize Data (In-place sanitization compatible with Express 5 getter properties)
+app.use((req, res, next) => {
+  if (req.body) mongoSanitize.sanitize(req.body);
+  if (req.params) mongoSanitize.sanitize(req.params);
+  if (req.query) mongoSanitize.sanitize(req.query);
+  next();
+});
 
 //Set Security Headers ************************************************
 app.use(helmet());
diff --git a/tests/mongoSanitize.test.js b/tests/mongoSanitize.test.js
new file mode 100644
index 0000000..03145ab
--- /dev/null
+++ b/tests/mongoSanitize.test.js
@@ -0,0 +1,25 @@
+const request = require("supertest");
+const app = require("../index");
+
+describe("NoSQL Injection Prevention (mongoSanitize)", () => {
+  it("should sanitize $ operators from request body", async () => {
+    const agent = request.agent(app);
+
+    // Fetch CSRF Token
+    const csrfRes = await agent.get("/api/v1/auth/csrf-token");
+    const csrfToken = csrfRes.body.csrfToken;
+
+    // Attempt login with NoSQL injection operator in email field
+    const res = await agent
+      .post("/api/v1/auth/login")
+      .set("x-csrf-token", csrfToken)
+      .send({
+        email: { $gt: "" },
+        password: "password123",
+      });
+
+    // Should fail with 400 or 401 instead of internal server error
+    expect(res.status).not.toBe(500);
+    expect(res.body.success).toBe(false);
+  });
+});