XML injection is a vulnerability that arises from a lack of proper validation and sanitization of user input before incorporating it into the XML configuration files or streams. This oversight allows an attacker to exploit the application by injecting malicious XML content. By manipulating the XML structure or introducing malicious entities, an attacker can potentially disrupt the application logic, tamper with data, or extract sensitive information.

=== "Dart"
	```dart
	import 'dart:convert';
	import 'dart:io';
	
	import 'package:flutter/material.dart';
	import 'package:path_provider/path_provider.dart';
	
	void main() {
	  runApp(MyApp());
	}
	
	class MyApp extends StatelessWidget {
	  @override
	  Widget build(BuildContext context) {
	    return MaterialApp(
	      title: 'XML Injection Demo',
	      theme: ThemeData(
	        primarySwatch: Colors.blue,
	      ),
	      home: MyHomePage(),
	    );
	  }
	}
	
	class MyHomePage extends StatefulWidget {
	  @override
	  _MyHomePageState createState() => _MyHomePageState();
	}
	
	class _MyHomePageState extends State<MyHomePage> {
	  final TextEditingController _usernameController = TextEditingController();
	  final TextEditingController _passwordController = TextEditingController();
	
	  @override
	  void dispose() {
	    _usernameController.dispose();
	    _passwordController.dispose();
	    super.dispose();
	  }
	
	  Future<void> saveConfigFile() async {
	    final directory = await getApplicationDocumentsDirectory();
	    final configFile = File('${directory.path}/config.xml');
	
	    // Create XML data
	    final xmlData = '''
	    <root>
	      <username>${_usernameController.text}</username>
	      <password>${_passwordController.text}</password>
	    </root>
	    ''';
	
	    // Save the XML to the configuration file
	    await configFile.writeAsString(xmlData);
	  }
	
	  void login() {
	    final username = _usernameController.text;
	    final password = _passwordController.text;
	
	    // Perform login logic
	    print('Performing login with username: $username and password: $password');
	  }
	
	  @override
	  Widget build(BuildContext context) {
	    return Scaffold(
	      appBar: AppBar(
	        title: Text('XML Injection Demo'),
	      ),
	      body: Padding(
	        padding: EdgeInsets.all(16.0),
	        child: Column(
	          crossAxisAlignment: CrossAxisAlignment.start,
	          children: [
	            Text('Enter username:'),
	            TextField(
	              controller: _usernameController,
	            ),
	            SizedBox(height: 16.0),
	            Text('Enter password:'),
	            TextField(
	              controller: _passwordController,
	              obscureText: true,
	            ),
	            SizedBox(height: 16.0),
	            ElevatedButton(
	              onPressed: () async {
	                await saveConfigFile();
	                login();
	              },
	              child: Text('Login'),
	            ),
	          ],
	        ),
	      ),
	    );
	  }
	}
	```


=== "Swift"
	```swift
	import SwiftUI
	
	struct ContentView: View {
	    @State private var username = ""
	    @State private var password = ""
	    
	    var body: some View {
	        VStack {
	            Text("Enter username:")
	            TextField("Username", text: $username)
	                .textFieldStyle(RoundedBorderTextFieldStyle())
	            
	            Text("Enter password:")
	            SecureField("Password", text: $password)
	                .textFieldStyle(RoundedBorderTextFieldStyle())
	            
	            Button(action: {
	                saveConfigFile()
	                login()
	            }) {
	                Text("Login")
	            }
	        }
	        .padding()
	    }
	    
	    func saveConfigFile() {
	        // Create XML data
	        let xmlData = '''
	        <root>
	          <username>\(username)</username>
	          <password>\(password)</password>
	        </root>
	        '''
	        
	        // Save the XML to the configuration file
	        let configFilePath = "config.xml"
	        do {
	            try xmlData.write(toFile: configFilePath, atomically: true, encoding: .utf8)
	        } catch {
	            print("Failed to write XML to file: \(error)")
	        }
	    }
	    
	    func login() {
	        // Perform login logic
	        print("Performing login with username: \(username) and password: \(password)")
	    }
	}
	
	@main
	struct XMLInjectionApp: App {
	    var body: some Scene {
	        WindowGroup {
	            ContentView()
	        }
	    }
	}
	```


=== "Kotlin"
	```kotlin
	import android.os.Bundle
	import android.widget.Button
	import android.widget.EditText
	import android.widget.Toast
	import androidx.appcompat.app.AppCompatActivity
	import java.io.File
	import javax.xml.parsers.DocumentBuilderFactory
	import javax.xml.transform.TransformerFactory
	import javax.xml.transform.dom.DOMSource
	import javax.xml.transform.stream.StreamResult
	
	class MainActivity : AppCompatActivity() {
	
	    private lateinit var usernameEditText: EditText
	    private lateinit var passwordEditText: EditText
	    private lateinit var loginButton: Button
	
	    override fun onCreate(savedInstanceState: Bundle?) {
	        super.onCreate(savedInstanceState)
	        setContentView(R.layout.activity_main)
	
	        usernameEditText = findViewById(R.id.usernameEditText)
	        passwordEditText = findViewById(R.id.passwordEditText)
	        loginButton = findViewById(R.id.loginButton)
	
	        loginButton.setOnClickListener {
	            val username = usernameEditText.text.toString()
	            val password = passwordEditText.text.toString()
	
	            saveConfigFile(username, password)
	            login(username, password)
	        }
	    }
	
	    private fun saveConfigFile(username: String, password: String) {
	        val configFilePath = "config.xml"
	
	        try {
	            val configFile = File(configFilePath)
	            val xmlData = configFile.readText()
	
	            val docBuilder = DocumentBuilderFactory.newInstance().newDocumentBuilder()
	            val doc = docBuilder.parse(xmlData.byteInputStream())
	            doc.documentElement.normalize()
	
	            val root = doc.documentElement
	
	            root.getElementsByTagName("username").item(0).textContent = username
	            root.getElementsByTagName("password").item(0).textContent = password
	
	            val transformer = TransformerFactory.newInstance().newTransformer()
	            val result = StreamResult(configFile)
	            val source = DOMSource(doc)
	            transformer.transform(source, result)
	        } catch (e: Exception) {
	            Toast.makeText(this, "Failed to save configuration file", Toast.LENGTH_SHORT).show()
	        }
	    }
	
	    private fun login(username: String, password: String) {
	        // Perform login logic
	        Toast.makeText(this, "Performing login with username: $username and password: $password", Toast.LENGTH_SHORT).show()
	    }
	}
	```

