CVE-2025-26420 affects Android’s permission flow, specifically in the GrantPermissionsActivity.java component. This post explains how attackers can exploit its permission overload logic — tricking users into allowing wrong permissions, with code snippets, simple language, and exclusive detail.

What Is CVE-2025-26420?

CVE-2025-26420 is a vulnerability in Android’s GrantPermissionsActivity.java file. This component shows users a list of permissions an app asks for at install time. Due to the way multiple functions in this file were handling permission requests, a malicious app could mix in dangerous permissions with less alarming ones, overloading the dialog and causing users (or even the system UI) to grant *the wrong* permissions automatically — no extra steps needed.

Normally, when you install or update an app on Android, you may see a dialog like

> “Allow ExampleApp to access your location, camera, contacts, and storage?”

You can grant or deny these as you see fit.

But, with CVE-2025-26420, if an app cleverly requests many permissions at once — especially groups that look similar — the dialog can confuse users *or system grant logic* and slip in a dangerous permission (like READ_SMS or SYSTEM_ALERT_WINDOW) without your realizing.

In vulnerable versions, the GrantPermissionsActivity.java code failed to clearly separate or limit permission requests, leading to overload situations.

Code Deep Dive: The Vulnerable Logic

Below is a simplified snippet based on the real vulnerable logic. (For legal reasons, this is *educational pseudocode* based on public analysis, not from decompiled Android source.)

// GrantPermissionsActivity.java

private void requestPermissions(String[] permissions) {
    List<String> requested = new ArrayList<>();
    for (String perm : permissions) {
        if (!alreadyGranted(perm)) {
            // No adequate filtering or grouping...
            requested.add(perm);
        }
    }
    showPermissionDialog(requested);
}

The issue? This activity batches *all* requested permissions into a single dialog or grant pass. If an app asks—even indirectly—for many, the system can end up granting *all* if the user taps “Allow” just to get rid of the dialog. Automated grant (like “Allow all” in some OEM ROMs, or initial setup flows) further increases risk.

Consider a real-world example

<!-- Manifest from a malicious app -->
<uses-permission android:name="android.permission.READ_CONTACTS" />
<uses-permission android:name="android.permission.READ_SMS" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
<!-- ... more ... -->

If all of these are requested at once and shown in a single overloaded dialog, the risk of misgranting missiles.

Exploitation Scenario

1. App install or update: Malicious app requests 8–15 permissions, including a dangerous one (like SMS).
2. Permission dialog appears: Overloaded with requests. User either agrees unintentionally or, on some devices, system or automation (like device management tools) grants all.
3. Vulnerable logic: Fails to limit or properly alert user of sensitive permission difference. Dangerous permission is granted among the noise.

App escalates privilege: Now it can read SMS, overlay UI, etc.—without explicit user OK.

No further steps needed. That’s local privilege escalation.

Attackers create an app with a manifest like

<manifest>
    <uses-permission android:name="android.permission.READ_CONTACTS" />
    <uses-permission android:name="android.permission.READ_CALENDAR" />
    <uses-permission android:name="android.permission.READ_SMS" />
    <!-- Add more harmless ones to overload -->
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.INTERNET" />
    <!-- ... -->
</manifest>

When installed, all are requested together due to the buggy batching.

How To Protect Yourself

- Update your Android device: Security patches for this CVE will be pushed by Google. See Android Security Bulletins for your build.

References

- Android Security Bulletins (Official)
- CVE-2025-26420 (CVE Details)
- AOSP Source for GrantPermissionsActivity.java (for latest—may be fixed)

Conclusion

CVE-2025-26420 is a prime example of how UX and programming oversights—even in system-level permission handling—can endanger user privacy and system integrity. The lesson: Always separate dangerous permission requests, and update Android regularly!

For developers: Audit your permission request flows and warn users clearly, especially if your app needs more than a few dangerous permissions!


Have questions? Drop your comments below, and share this post to help others stay safe!

Timeline

Published on: 09/04/2025 18:15:39 UTC
Last modified on: 09/05/2025 18:55:46 UTC