diff --git a/js/account.js b/js/account.js
index 0b1da3f..8647358 100644
--- a/js/account.js
+++ b/js/account.js
@@ -118,13 +118,13 @@ function renderOrders() {
                 c => c.id === order.course_id
             );
             orderName = course ? course.name : 
-                       `Курс #${order.course_id}`;
+                       `Курс #${esc(order.course_id)}`;
         } else if (order.tutor_id && order.tutor_id > 0) {
             const tutor = AccountState.tutors.find(
                 t => t.id === order.tutor_id
             );
             orderName = tutor ? `Репетитор: ${tutor.name}` : 
-                       `Репетитор #${order.tutor_id}`;
+                       `Репетитор #${esc(order.tutor_id)}`;
         }
 
         const orderDate = formatDateTimeWithoutSeconds(
@@ -133,22 +133,22 @@ function renderOrders() {
         );
 
         tr.innerHTML = `
-            <td>${orderNumber}</td>
-            <td>${orderName}</td>
-            <td>${orderDate}</td>
+            <td>${esc(orderNumber)}</td>
+            <td>${esc(orderName)}</td>
+            <td>${esc(orderDate)}</td>
             <td>${formatPrice(order.price)}</td>
             <td>
                 <div class="btn-group btn-group-sm" role="group">
                     <button class="btn btn-info view-order-btn" 
-                            data-order-id="${order.id}">
+                            data-order-id="${esc(order.id)}">
                         <i class="bi bi-eye"></i>
                     </button>
                     <button class="btn btn-warning edit-order-btn" 
-                            data-order-id="${order.id}">
+                            data-order-id="${esc(order.id)}">
                         <i class="bi bi-pencil"></i>
                     </button>
                     <button class="btn btn-danger delete-order-btn" 
-                            data-order-id="${order.id}">
+                            data-order-id="${esc(order.id)}">
                         <i class="bi bi-trash"></i>
                     </button>
                 </div>
@@ -254,7 +254,7 @@ function viewOrderDetails(orderId) {
         if (course) {
             orderTitle = course.name;
             teacherInfo = `<p><strong>Преподаватель:</strong> 
-                          ${course.teacher}</p>`;
+                          ${esc(course.teacher)}</p>`;
         }
     } else if (order.tutor_id && order.tutor_id > 0) {
         const tutor = AccountState.tutors.find(
@@ -284,7 +284,7 @@ function viewOrderDetails(orderId) {
         options.push('Доступ к интерактивной онлайн-платформе (+50%)');
 
     const optionsBadges = options.map(opt => 
-        `<span class="badge bg-secondary me-1 mb-1">${opt}</span>`
+        `<span class="badge bg-secondary me-1 mb-1">${esc(opt)}</span>`
     ).join('');
 
     const contactData = ContactDataStorage.get(order.id);
@@ -294,16 +294,16 @@ function viewOrderDetails(orderId) {
         contactInfo = `
             <hr>
             <h6>Контактные данные:</h6>
-            <p><strong>Имя:</strong> ${contactData.name}</p>
-            <p><strong>Телефон:</strong> ${contactData.phone}</p>
-            <p><strong>Email:</strong> ${contactData.email}</p>
+            <p><strong>Имя:</strong> ${esc(contactData.name)}</p>
+            <p><strong>Телефон:</strong> ${esc(contactData.phone)}</p>
+            <p><strong>Email:</strong> ${esc(contactData.email)}</p>
             ${contactData.message ? 
               `<p><strong>Сообщение:</strong> ${contactData.message}</p>` 
               : ''}
         `;
     }
 
-    let detailsHTML = `<h5>${orderTitle}</h5>${teacherInfo}`;
+    let detailsHTML = `<h5>${esc(orderTitle)}</h5>${teacherInfo}`;
     let priceLabel = '';
 
     if (order.course_id && order.course_id > 0) {
@@ -312,9 +312,9 @@ function viewOrderDetails(orderId) {
                ${formatDate(order.date_start)}</p>
             <p><strong>Время:</strong> ${formatTime(order.time_start)}</p>
             <p><strong>Продолжительность:</strong>
-               ${order.duration} часов</p>
+               ${esc(order.duration)} часов</p>
             <p><strong>Количество студентов:</strong>
-               ${order.persons}</p>
+               ${esc(order.persons)}</p>
             ${options.length > 0 ?
               `<p><strong>Выбранные опции:</strong><br>${optionsBadges}</p>`
               : ''}
@@ -328,9 +328,9 @@ function viewOrderDetails(orderId) {
     }
 
     detailsHTML += `
-        ${contactInfo}
+        ${esc(contactInfo)}
         <hr>
-        <h5>${priceLabel}</h5>
+        <h5>${esc(priceLabel)}</h5>
     `;
 
     content.innerHTML = detailsHTML;
diff --git a/js/app.js b/js/app.js
index a7d5472..a948f64 100644
--- a/js/app.js
+++ b/js/app.js
@@ -163,7 +163,7 @@ function renderCourses() {
         
         item.innerHTML = `
             <div class="course-item-header">
-                <h5 class="course-item-title">${course.name}</h5>
+                <h5 class="course-item-title">${esc(course.name)}</h5>
                 <span class="badge level-badge 
                       ${getLevelBadgeClass(course.level)}">
                     ${getLevelText(course.level)}
@@ -175,12 +175,12 @@ function renderCourses() {
             <div class="course-item-details">
                 <div>
                     <i class="bi bi-person"></i>
-                    <span>${course.teacher}</span>
+                    <span>${esc(course.teacher)}</span>
                 </div>
                 <div>
                     <i class="bi bi-clock"></i>
-                    <span>${course.total_length} недель, 
-                          ${course.week_length} ч/нед</span>
+                    <span>${esc(course.total_length)} недель, 
+                          ${esc(course.week_length)} ч/нед</span>
                 </div>
                 <div>
                     <i class="bi bi-cash"></i>
@@ -582,13 +582,13 @@ function renderTutors() {
                     <i class="bi bi-person-circle"></i>
                 </div>
             </td>
-            <td>${tutor.name}</td>
+            <td>${esc(tutor.name)}</td>
             <td><span class="badge level-badge
                 ${getLevelBadgeClass(tutor.language_level)}">
                 ${getLevelText(tutor.language_level)}
             </span></td>
             <td>${tutor.languages_offered.join(', ')}</td>
-            <td>${tutor.work_experience} лет</td>
+            <td>${esc(tutor.work_experience)} лет</td>
             <td>${formatPrice(tutor.price_per_hour)}/час</td>
             <td>
                 <button class="btn btn-sm btn-primary select-tutor-btn">
diff --git a/js/map.js b/js/map.js
index 5807211..78d85e0 100644
--- a/js/map.js
+++ b/js/map.js
@@ -109,12 +109,12 @@ function initMap() {
                 const placemark = new ymaps.Placemark(
                     resource.coords,
                     {
-                        balloonContentHeader: `<strong>${resource.name}</strong>`,
+                        balloonContentHeader: `<strong>${esc(resource.name)}</strong>`,
                         balloonContentBody: `
-                            <p class="mb-1"><i class="bi bi-geo-alt"></i> ${resource.address}</p>
-                            <p class="mb-1"><i class="bi bi-clock"></i> ${resource.hours}</p>
-                            <p class="mb-1"><i class="bi bi-telephone"></i> ${resource.phone}</p>
-                            <p class="mb-0"><i class="bi bi-info-circle"></i> ${resource.description}</p>
+                            <p class="mb-1"><i class="bi bi-geo-alt"></i> ${esc(resource.address)}</p>
+                            <p class="mb-1"><i class="bi bi-clock"></i> ${esc(resource.hours)}</p>
+                            <p class="mb-1"><i class="bi bi-telephone"></i> ${esc(resource.phone)}</p>
+                            <p class="mb-0"><i class="bi bi-info-circle"></i> ${esc(resource.description)}</p>
                         `,
                         hintContent: resource.name
                     },
@@ -130,11 +130,11 @@ function initMap() {
                     const item = document.createElement('div');
                     item.className = 'resource-item';
                     item.innerHTML = `
-                        <h6>${resource.name}</h6>
-                        <p class="mb-1"><i class="bi bi-geo-alt me-1"></i>${resource.address}</p>
-                        <p class="mb-1"><i class="bi bi-clock me-1"></i>${resource.hours}</p>
-                        <p class="mb-1"><i class="bi bi-telephone me-1"></i>${resource.phone}</p>
-                        <p class="mb-0 text-muted small">${resource.description}</p>
+                        <h6>${esc(resource.name)}</h6>
+                        <p class="mb-1"><i class="bi bi-geo-alt me-1"></i>${esc(resource.address)}</p>
+                        <p class="mb-1"><i class="bi bi-clock me-1"></i>${esc(resource.hours)}</p>
+                        <p class="mb-1"><i class="bi bi-telephone me-1"></i>${esc(resource.phone)}</p>
+                        <p class="mb-0 text-muted small">${esc(resource.description)}</p>
                     `;
 
                     item.addEventListener('click', () => {
diff --git a/js/utils.js b/js/utils.js
index fdf6704..ff5758c 100644
--- a/js/utils.js
+++ b/js/utils.js
@@ -1,3 +1,14 @@
+// Экранирование данных перед вставкой в HTML (данные приходят из общего учебного API);
+// utils.js подключается раньше app.js, account.js и map.js, поэтому esc() доступна во всех них
+function esc(value) {
+    return String(value ?? '')
+        .replace(/&/g, '&amp;')
+        .replace(/</g, '&lt;')
+        .replace(/>/g, '&gt;')
+        .replace(/"/g, '&quot;')
+        .replace(/'/g, '&#39;');
+}
+
 // Показать уведомление с автоматическим удалением
 function showNotification(message, type = 'info') {
     const notificationArea = document.getElementById('notificationArea');
@@ -24,8 +35,8 @@ function showNotification(message, type = 'info') {
     notification.className = `alert ${alertClass} alert-dismissible
                              fade show notification`;
     notification.innerHTML = `
-        <i class="bi ${iconClass} me-2"></i>
-        ${message}
+        <i class="bi ${esc(iconClass)} me-2"></i>
+        ${esc(message)}
         <button type="button" class="btn-close"
                 data-bs-dismiss="alert"></button>
     `;