CVE-2026-56294

capacitor-native-biometric before 12.128.2 contains an authentication bypass vulnerability where the onAuthenticationSucceeded() method fails to validate CryptoObject parameters. Attackers can hook the onAuthenticationSucceeded() function using dynamic instrumentation to bypass biometric authentication without valid credentials.

capacitor-native-biometric before 12.128.2 contains an authentication bypass vulnerability where the onAuthenticationSucceeded() method fails to validate CryptoObject parameters. Attackers can hook the onAuthenticationSucceeded() function using dynamic instrumentation to bypass biometric authentication without valid credentials.

capacitor-native-biometric before 12.128.2 contains an authentication bypass vulnerability where the onAuthenticationSucceeded() method fails to validate CryptoObject parameters. Attackers can hook the onAuthenticationSucceeded() function using dynamic instrumentation to bypass biometric authentication without valid credentials.

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:

@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.

1. 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:

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

Yarn Alternative:

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

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

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:

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

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

npx cap init
npx cap add android

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

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

5. 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) {
       …

capacitor-native-biometric before 12.128.2 contains an authentication bypass vulnerability where the onAuthenticationSucceeded() method fails to validate CryptoObject parameters. Attackers can hook the onAuthenticationSucceeded() function using dynamic instrumentation to bypass biometric authentication without valid credentials.

capacitor-native-biometric before 12.128.2 contains an authentication bypass vulnerability where the onAuthenticationSucceeded() method fails to validate CryptoObject parameters. Attackers can hook the onAuthenticationSucceeded() function using dynamic instrumentation to bypass biometric authentication without valid credentials.

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:

@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.

1. 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:

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

Yarn Alternative:

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

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

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:

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

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

npx cap init
npx cap add android

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

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

5. 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) {
       …