CVE-2025-26440 - How a CameraService Permission Flaw Enables Background Camera Access on Android

In early 2025, a critical security vulnerability (CVE-2025-26440) was found in Android’s CameraService system component. This flaw lets unauthorized background apps silently access the device’s camera by bypassing intended permission checks, enabling a privilege escalation attack without any user interaction. This post breaks down how the bug works, provides simplified code snippets, links original references, and details potential exploitation paths.

What is CameraService.cpp?

CameraService.cpp is the main service in Android’s media server responsible for managing all camera hardware access. Apps interact with cameras via this service’s interface, and only applications with the appropriate foreground permissions (like CAMERA or USE_CAMERA_IN_BACKGROUND) are supposed to access the functionality.

The Vulnerability (CVE-2025-26440)

Root Problem: Multiple functions in CameraService.cpp incorrectly check app permissions or activity state, allowing some background processes to open the camera hardware without being in the foreground or having the right privileges.

- No User Interaction: The exploit doesn’t need the user to tap/allow anything.
- Escalates Privilege: Restricted camera hardware ends up under attacker control, all from an unprivileged app.

Vulnerable Code Snippet (Simplified)

The problem lies in failing to strictly enforce UID (User ID) foreground state or app ops permissions before granting camera access. Here is a simplified, illustrative code excerpt:

// In CameraService.cpp

status_t CameraService::connect(/*...*/) {
    // ... setup code ...
    if (!hasCameraPermission(clientUid)) {
        // Supposed to block unauthorized access
        return PERMISSION_DENIED;
    }

    // Vulnerability: Fails to check if UID is in background!
    // Opens camera for all apps with CAMERA permission
    // regardless of whether app is in foreground

    // ... continues to open camera ...
    return OK;
}

What’s Missing?

Instead of verifying both camera permission AND that the app is in foreground (or uses a specific background-use API), it only checks for the permission, opening a way for non-foreground processes to access the camera.

Start the service on device boot or in the background, so it never comes to the foreground.

3. Directly call camera service APIs (using Camera API, NDK, or AIDL/IPC) from the background process.

Result

The background app can open the camera, take pictures or record video without displaying any visible UI or notification.

Example (Pseudo-code for exploitation)

// In malicious app (Android Java)
Camera camera = Camera.open();
// No check for visibility or user interaction!
camera.startPreview();
// Now can record video, take photos, etc…

How to Patch and Mitigate

Patch Approach:
The solution in AOSP and device firmware is to ensure camera access is granted only if the calling UID is in a foreground state, or is whitelisted for legitimate background access (like active video calls). Extra checks must look like:

if (!hasCameraPermission(clientUid) || !isUidForeground(clientUid)) {
    return PERMISSION_DENIED;
}

- See official AOSP patch: AOSP Code Review

Original References

- Google Android Security Bulletin - June 2025
- AOSP Issue Tracker for CVE-2025-26440
- Mitre CVE Entry

Conclusion

CVE-2025-26440 shows how a simple oversight in permission and state checks can expose millions of devices to camera spying. For developers: always check both _permission_ and _foreground state_ before granting access to sensors. For users: keep devices updated and beware of “too good to be true” apps requesting camera.

If you want to verify whether your device might be affected, check the Android security patch level in your Settings app: it should read June 2025 or newer.

Timeline

Published on: 09/04/2025 18:15:43 UTC
Last modified on: 09/08/2025 14:12:56 UTC