diff --git a/SECURITY-FIXES.md b/SECURITY-FIXES.md
new file mode 100644
index 0000000..f53dbd6
--- /dev/null
+++ b/SECURITY-FIXES.md
@@ -0,0 +1,579 @@
+# Security Fixes Implementation Guide
+
+This document contains all the code changes required to fix the 3 critical security vulnerabilities identified in the audit report.
+
+**Status**: Ready for implementation
+**Date**: December 13, 2025
+**Priority**: P0 (Critical) - Must be implemented before production
+
+---
+
+## Fix 1: Insecure Random Number Generation (CRITICAL)
+
+**CVSS Score**: 8.1 (High)
+**Location**: `backend/src/features/documents/api/documents.controller.ts`
+**Lines**: 321-324
+
+### Current Code (INSECURE):
+```typescript
+function cryptoRandom(): string {
+  // Safe unique suffix for object keys
+  return Math.random().toString(36).slice(2) + Date.now().toString(36);
+}
+```
+
+### Required Changes:
+
+#### Step 1: Add crypto import
+**File**: `backend/src/features/documents/api/documents.controller.ts`
+**Location**: Line 8 (after existing imports)
+
+```typescript
+import crypto from 'crypto';
+```
+
+#### Step 2: Replace cryptoRandom function
+**File**: `backend/src/features/documents/api/documents.controller.ts`
+**Location**: Lines 321-324
+
+```typescript
+function cryptoRandom(): string {
+  // Cryptographically secure random suffix for object keys
+  return crypto.randomBytes(32).toString('hex');
+}
+```
+
+### Testing:
+```bash
+# Rebuild containers
+make rebuild
+
+# Verify document uploads still work
+# Test that storage keys are now unpredictable
+```
+
+---
+
+## Fix 2: Inadequate File Upload Validation (HIGH)
+
+**CVSS Score**: 7.5 (High)
+**Location**: `backend/src/features/documents/api/documents.controller.ts`
+**Lines**: 205-216 and entire upload method
+
+### Required Changes:
+
+#### Step 1: Add file-type package
+**File**: `backend/package.json`
+**Location**: dependencies section
+
+Add this line to dependencies:
+```json
+"file-type": "^19.8.0"
+```
+
+#### Step 2: Add imports
+**File**: `backend/src/features/documents/api/documents.controller.ts`
+**Location**: After line 7 (with other imports)
+
+```typescript
+import { fileTypeFromBuffer } from 'file-type';
+import { Readable } from 'stream';
+```
+
+#### Step 3: Replace entire upload method
+**File**: `backend/src/features/documents/api/documents.controller.ts`
+**Location**: Lines 175-268 (entire `upload` method)
+
+```typescript
+async upload(request: FastifyRequest<{ Params: IdParams }>, reply: FastifyReply) {
+  const userId = (request as any).user?.sub as string;
+  const documentId = request.params.id;
+
+  logger.info('Document upload requested', {
+    operation: 'documents.upload',
+    user_id: userId,
+    document_id: documentId,
+  });
+
+  const doc = await this.service.getDocument(userId, documentId);
+  if (!doc) {
+    logger.warn('Document not found for upload', {
+      operation: 'documents.upload.not_found',
+      user_id: userId,
+      document_id: documentId,
+    });
+    return reply.code(404).send({ error: 'Not Found' });
+  }
+
+  const mp = await (request as any).file({ limits: { files: 1 } });
+  if (!mp) {
+    logger.warn('No file provided for upload', {
+      operation: 'documents.upload.no_file',
+      user_id: userId,
+      document_id: documentId,
+    });
+    return reply.code(400).send({ error: 'Bad Request', message: 'No file provided' });
+  }
+
+  // Define allowed MIME types and their corresponding magic byte signatures
+  const allowedTypes = new Map([
+    ['application/pdf', new Set(['application/pdf'])],
+    ['image/jpeg', new Set(['image/jpeg'])],
+    ['image/png', new Set(['image/png'])],
+  ]);
+
+  const contentType = mp.mimetype as string | undefined;
+  if (!contentType || !allowedTypes.has(contentType)) {
+    logger.warn('Unsupported file type for upload (header validation)', {
+      operation: 'documents.upload.unsupported_type',
+      user_id: userId,
+      document_id: documentId,
+      content_type: contentType,
+      file_name: mp.filename,
+    });
+    return reply.code(415).send({
+      error: 'Unsupported Media Type',
+      message: 'Only PDF, JPEG, and PNG files are allowed'
+    });
+  }
+
+  // Read first 4100 bytes to detect file type via magic bytes
+  const chunks: Buffer[] = [];
+  let totalBytes = 0;
+  const targetBytes = 4100;
+
+  for await (const chunk of mp.file) {
+    chunks.push(chunk);
+    totalBytes += chunk.length;
+    if (totalBytes >= targetBytes) {
+      break;
+    }
+  }
+
+  const headerBuffer = Buffer.concat(chunks);
+
+  // Validate actual file content using magic bytes
+  const detectedType = await fileTypeFromBuffer(headerBuffer);
+
+  if (!detectedType) {
+    logger.warn('Unable to detect file type from content', {
+      operation: 'documents.upload.type_detection_failed',
+      user_id: userId,
+      document_id: documentId,
+      content_type: contentType,
+      file_name: mp.filename,
+    });
+    return reply.code(415).send({
+      error: 'Unsupported Media Type',
+      message: 'Unable to verify file type from content'
+    });
+  }
+
+  // Verify detected type matches claimed Content-Type
+  const allowedDetectedTypes = allowedTypes.get(contentType);
+  if (!allowedDetectedTypes || !allowedDetectedTypes.has(detectedType.mime)) {
+    logger.warn('File content does not match Content-Type header', {
+      operation: 'documents.upload.type_mismatch',
+      user_id: userId,
+      document_id: documentId,
+      claimed_type: contentType,
+      detected_type: detectedType.mime,
+      file_name: mp.filename,
+    });
+    return reply.code(415).send({
+      error: 'Unsupported Media Type',
+      message: `File content (${detectedType.mime}) does not match claimed type (${contentType})`
+    });
+  }
+
+  const originalName: string = mp.filename || 'upload';
+  const ext = (() => {
+    const e = path.extname(originalName).replace(/^\./, '').toLowerCase();
+    if (e) return e;
+    if (contentType === 'application/pdf') return 'pdf';
+    if (contentType === 'image/jpeg') return 'jpg';
+    if (contentType === 'image/png') return 'png';
+    return 'bin';
+  })();
+
+  class CountingStream extends Transform {
+    public bytes = 0;
+    override _transform(chunk: any, _enc: BufferEncoding, cb: TransformCallback) {
+      this.bytes += chunk.length || 0;
+      cb(null, chunk);
+    }
+  }
+
+  const counter = new CountingStream();
+
+  // Create a new readable stream from the header buffer + remaining file chunks
+  const headerStream = Readable.from([headerBuffer]);
+  const remainingStream = mp.file;
+
+  // Pipe header first, then remaining content through counter
+  headerStream.pipe(counter, { end: false });
+  headerStream.on('end', () => {
+    remainingStream.pipe(counter);
+  });
+
+  const storage = getStorageService();
+  const bucket = 'documents';
+  const version = 'v1';
+  const unique = cryptoRandom();
+  const key = `documents/${userId}/${doc.vehicle_id}/${doc.id}/${version}/${unique}.${ext}`;
+
+  await storage.putObject(bucket, key, counter, contentType, { 'x-original-filename': originalName });
+
+  const updated = await this.service['repo'].updateStorageMeta(doc.id, userId, {
+    storage_bucket: bucket,
+    storage_key: key,
+    file_name: originalName,
+    content_type: contentType,
+    file_size: counter.bytes,
+    file_hash: null,
+  });
+
+  logger.info('Document upload completed', {
+    operation: 'documents.upload.success',
+    user_id: userId,
+    document_id: documentId,
+    vehicle_id: doc.vehicle_id,
+    file_name: originalName,
+    content_type: contentType,
+    detected_type: detectedType.mime,
+    file_size: counter.bytes,
+    storage_key: key,
+  });
+
+  return reply.code(200).send(updated);
+}
+```
+
+### Testing:
+```bash
+# Install new dependency
+cd backend && npm install
+
+# Rebuild containers
+make rebuild
+
+# Test legitimate files
+# - Upload PDF, JPEG, PNG - should succeed
+
+# Test attack scenarios
+# - Rename .exe to .pdf - should be REJECTED
+# - Spoof Content-Type header - should be REJECTED
+```
+
+---
+
+## Fix 3: Google Maps API Key Exposure (HIGH)
+
+**CVSS Score**: 6.5 (Medium-High)
+**Location**: Multiple files in `backend/src/features/stations/`
+
+### Required Changes:
+
+#### Backend Changes
+
+##### Step 1: Update Google Maps Client
+**File**: `backend/src/features/stations/external/google-maps/google-maps.client.ts`
+
+**Change 1**: Update `transformPlaceToStation` method (lines 76-95)
+```typescript
+private transformPlaceToStation(place: GooglePlace, searchLat: number, searchLng: number): Station {
+  const distance = this.calculateDistance(
+    searchLat,
+    searchLng,
+    place.geometry.location.lat,
+    place.geometry.location.lng
+  );
+
+  // Store photo reference instead of full URL to avoid exposing API key
+  let photoReference: string | undefined;
+  if (place.photos && place.photos.length > 0 && place.photos[0]) {
+    photoReference = place.photos[0].photo_reference;
+  }
+
+  const station: Station = {
+    id: place.place_id,
+    placeId: place.place_id,
+    name: place.name,
+    address: place.vicinity,
+    latitude: place.geometry.location.lat,
+    longitude: place.geometry.location.lng,
+    distance
+  };
+
+  if (photoReference !== undefined) {
+    station.photoReference = photoReference;
+  }
+
+  if (place.opening_hours?.open_now !== undefined) {
+    station.isOpen = place.opening_hours.open_now;
+  }
+
+  if (place.rating !== undefined) {
+    station.rating = place.rating;
+  }
+
+  return station;
+}
+```
+
+**Change 2**: Add new method after `transformPlaceToStation`
+```typescript
+/**
+ * Fetch photo from Google Maps API using photo reference
+ * Used by photo proxy endpoint to serve photos without exposing API key
+ */
+async fetchPhoto(photoReference: string, maxWidth: number = 400): Promise<Buffer> {
+  try {
+    const response = await axios.get(
+      `${this.baseURL}/photo`,
+      {
+        params: {
+          photo_reference: photoReference,
+          maxwidth: maxWidth,
+          key: this.apiKey
+        },
+        responseType: 'arraybuffer'
+      }
+    );
+
+    return Buffer.from(response.data);
+  } catch (error) {
+    logger.error('Failed to fetch photo from Google Maps', { error, photoReference });
+    throw error;
+  }
+}
+```
+
+##### Step 2: Update Station Type (Backend)
+**File**: `backend/src/features/stations/domain/stations.types.ts`
+**Line**: 20
+
+```typescript
+// OLD:
+photoUrl?: string;
+
+// NEW:
+photoReference?: string;
+```
+
+##### Step 3: Update Stations Controller
+**File**: `backend/src/features/stations/api/stations.controller.ts`
+
+**Add import** at the top:
+```typescript
+import { googleMapsClient } from '../external/google-maps/google-maps.client';
+```
+
+**Add method** after `removeSavedStation`:
+```typescript
+async getStationPhoto(request: FastifyRequest<{ Params: { reference: string } }>, reply: FastifyReply) {
+  try {
+    const { reference } = request.params;
+
+    if (!reference) {
+      return reply.code(400).send({
+        error: 'Bad Request',
+        message: 'Photo reference is required'
+      });
+    }
+
+    const photoBuffer = await googleMapsClient.fetchPhoto(reference);
+
+    return reply
+      .code(200)
+      .header('Content-Type', 'image/jpeg')
+      .header('Cache-Control', 'public, max-age=86400')
+      .send(photoBuffer);
+  } catch (error: any) {
+    logger.error('Error fetching station photo', {
+      error,
+      reference: request.params.reference
+    });
+    return reply.code(500).send({
+      error: 'Internal server error',
+      message: 'Failed to fetch station photo'
+    });
+  }
+}
+```
+
+##### Step 4: Update Stations Routes
+**File**: `backend/src/features/stations/api/stations.routes.ts`
+
+**Add route** before the closing `};`:
+```typescript
+// GET /api/stations/photo/:reference - Proxy for Google Maps photos
+fastify.get<{ Params: { reference: string } }>('/stations/photo/:reference', {
+  preHandler: [fastify.authenticate],
+  handler: stationsController.getStationPhoto.bind(stationsController)
+});
+```
+
+##### Step 5: Update Stations Service
+**File**: `backend/src/features/stations/domain/stations.service.ts`
+**Line**: 144
+
+```typescript
+// OLD:
+photoUrl: station?.photoUrl,
+
+// NEW:
+photoReference: station?.photoReference,
+```
+
+#### Frontend Changes
+
+##### Step 6: Update Station Type (Frontend)
+**File**: `frontend/src/features/stations/types/stations.types.ts`
+**Line**: 60
+
+```typescript
+// OLD:
+photoUrl?: string;
+
+// NEW:
+photoReference?: string;
+```
+
+##### Step 7: Create Photo Utils Helper
+**File**: `frontend/src/features/stations/utils/photo-utils.ts` (NEW FILE)
+
+```typescript
+/**
+ * @ai-summary Helper utilities for station photos
+ */
+
+/**
+ * Generate secure photo URL using backend proxy endpoint
+ * This prevents exposing the Google Maps API key to the frontend
+ */
+export function getStationPhotoUrl(photoReference: string | undefined): string | undefined {
+  if (!photoReference) {
+    return undefined;
+  }
+
+  return `/api/stations/photo/${encodeURIComponent(photoReference)}`;
+}
+```
+
+##### Step 8: Update StationCard Component
+**File**: `frontend/src/features/stations/components/StationCard.tsx`
+
+**Add import** at the top:
+```typescript
+import { getStationPhotoUrl } from '../utils/photo-utils';
+```
+
+**Update photo rendering** (lines 86-93):
+```typescript
+// OLD:
+{station.photoUrl && (
+  <CardMedia
+    component="img"
+    height="200"
+    image={station.photoUrl}
+    alt={station.name}
+    sx={{ objectFit: 'cover' }}
+  />
+)}
+
+// NEW:
+{station.photoReference && (
+  <CardMedia
+    component="img"
+    height="200"
+    image={getStationPhotoUrl(station.photoReference)}
+    alt={station.name}
+    sx={{ objectFit: 'cover' }}
+  />
+)}
+```
+
+### Testing:
+```bash
+# Rebuild containers
+make rebuild
+
+# Test station search with photos
+# Verify API key is NOT in network requests
+# Verify photos still load correctly
+# Test on mobile and desktop
+```
+
+---
+
+## Implementation Checklist
+
+- [ ] Apply Fix 1: Insecure Random Generation
+  - [ ] Add crypto import
+  - [ ] Replace cryptoRandom function
+  - [ ] Test document uploads
+
+- [ ] Apply Fix 2: File Upload Validation
+  - [ ] Add file-type to package.json
+  - [ ] Run npm install
+  - [ ] Add imports
+  - [ ] Replace upload method
+  - [ ] Test with legitimate files
+  - [ ] Test with malicious files
+
+- [ ] Apply Fix 3: API Key Exposure
+  - [ ] Update Google Maps client
+  - [ ] Update backend Station type
+  - [ ] Add controller method
+  - [ ] Add route
+  - [ ] Update service
+  - [ ] Update frontend Station type
+  - [ ] Create photo-utils.ts
+  - [ ] Update StationCard component
+  - [ ] Test photos load correctly
+  - [ ] Verify API key not in network
+
+- [ ] Run all tests
+  - [ ] Backend tests: `cd backend && npm test`
+  - [ ] Frontend tests: `cd frontend && npm test`
+
+- [ ] Rebuild and verify
+  - [ ] `make rebuild`
+  - [ ] Manual testing of all features
+  - [ ] Security verification (no API keys exposed)
+
+- [ ] Create git commit with security fixes
+
+---
+
+## Security Verification
+
+After implementing all fixes, verify:
+
+1. **Document Storage Keys**: Now using `crypto.randomBytes()` - unpredictable
+2. **File Upload**: Magic byte validation rejects spoofed files
+3. **Google Maps API**: Key never sent to frontend, all requests proxied
+
+Run security scan:
+```bash
+# Check for hardcoded secrets
+grep -r "AIza" backend/ frontend/
+# Should return no results
+
+# Verify crypto usage
+grep -r "Math.random()" backend/
+# Should return no results in production code
+```
+
+---
+
+## Post-Implementation
+
+After all fixes are applied and tested:
+
+1. Update AUDIT.md to reflect fixed status
+2. Commit changes with security fix message
+3. Run full test suite
+4. Deploy to staging for verification
+5. Schedule production deployment
diff --git a/backend/package.json b/backend/package.json
index 9c4259e..f4b32a0 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -33,7 +33,8 @@
     "@sinclair/typebox": "^0.31.28",
     "fastify-plugin": "^4.5.1",
     "@fastify/autoload": "^5.8.0",
-    "get-jwks": "^9.0.0"
+    "get-jwks": "^9.0.0",
+    "file-type": "^19.8.0"
   },
   "devDependencies": {
     "@types/node": "^20.10.0",
diff --git a/backend/src/features/documents/api/documents.controller.ts b/backend/src/features/documents/api/documents.controller.ts
index 2bcb765..a231a6d 100644
--- a/backend/src/features/documents/api/documents.controller.ts
+++ b/backend/src/features/documents/api/documents.controller.ts
@@ -5,6 +5,7 @@ import { getStorageService } from '../../../core/storage/storage.service';
 import { logger } from '../../../core/logging/logger';
 import path from 'path';
 import { Transform, TransformCallback } from 'stream';
+import crypto from 'crypto';
 
 export class DocumentsController {
   private readonly service = new DocumentsService();
@@ -319,6 +320,6 @@ export class DocumentsController {
 }
 
 function cryptoRandom(): string {
-  // Safe unique suffix for object keys
-  return Math.random().toString(36).slice(2) + Date.now().toString(36);
+  // Cryptographically secure random suffix for object keys
+  return crypto.randomBytes(32).toString('hex');
 }