The year 2025 has already seen a number of serious security flaws, and one of the latest involves Android: CVE-2025-26427. This vulnerability is all about a simple but critical “path traversal” bug in multiple spots across the Android system and apps — letting local attackers access sensitive data in your Android/data folder. In this deep dive, we'll explore how this flaw works, why it's dangerous, and show a practical example of exploitation. We’ll also link direct to the original references and advisories.

What is CVE-2025-26427?

CVE-2025-26427 is an Android local privilege escalation vulnerability caused by improper validation of file paths ("path traversal"). In simple terms, some Android apps and components fail to restrict user-supplied input used for file system access. That means someone can ask a vulnerable app to open or save data *outside* its intended sandbox, into places like the Android/data folder — or, even worse, into other apps' domains.

A successful exploit lets local attackers — people who already have some access on your device — escalate privileges by reading or overwriting files they should not be able to touch. No special system permissions are needed, but the user does need to interact (for example: opening a file provided by an attacker).

- Android Affected: Multiple versions; check Android Security Bulletin

Anatomy of the Path Traversal

Path traversal (aka directory traversal) exploits happen when code allows you to reach files outside an allowed folder using ../ (parent directory) tricks in a file path. Here’s a classic insecure function in Java/Android:

// BAD EXAMPLE: vulnerable to path traversal
public void saveToFile(Context context, String userInput) {
    File root = new File(context.getFilesDir(), "myapp");
    File target = new File(root, userInput);
    // could be /data/data/com.example.myapp/files/myapp/../../../../Android/data/otherapp/privatefile
    writeSomeData(target);
}

If an attacker gives userInput like ../../../../Android/data/otherapp/privatefile, the function ends up writing (or reading) unintended files.

How Could Attackers Exploit CVE-2025-26427?

To pull off this attack, the adversary needs some way to pass malicious file paths to a target Android app — usually via:

- Exploiting a 3rd party/sideloaded app with poor file validation

Victim opens it in a vulnerable app.

3. The malicious file contains a path like ../../data/com.android.settings/shared_prefs/settings.xml.

Demonstration: Sample Exploit Code

Below is a PoC (Proof of Concept) in Java/Android to *read* data from another app’s Android/data directory. This is a simplification; real-world exploitation would need user help.

// Example: Reading data from an unintended location via path traversal

public void onUserSelectFile(String userInputRelativePath) {
    File baseDir = new File(getFilesDir(), "imports");
    File dangerousTarget = new File(baseDir, userInputRelativePath);

    try (BufferedReader br = new BufferedReader(new FileReader(dangerousTarget))) {
        String line;
        while ((line = br.readLine()) != null) {
            Log.d("CVE202526427", "Read: " + line);
        }
    } catch (IOException e) {
        Log.w("CVE202526427", "Couldn't read file", e);
    }
}

// If the attacker supplies ../../../../Android/data/com.other.app/files/data.txt
// the above code could read sensitive info from another app's data.

Watch out for unusual file prompts and only open trusted attachments.

- Keep your device updated. The Android Security Team has released patches — see Android Security Bulletin – June 2025.

For Developers:
Always sanitize and validate user-supplied file paths. NEVER allow ../ to escape intended directories!

public boolean isSafePath(File base, File target) throws IOException {
    String basePath = base.getCanonicalPath();
    String targetPath = target.getCanonicalPath();
    return targetPath.startsWith(basePath + File.separator);
}

References & Further Reading

- Android Security Bulletin – June 2025
- CVE Record for CVE-2025-26427
- OWASP Path Traversal Cheat Sheet
- Reported fix: AOSP Commit (find commit referencing this CVE)

Bottom Line

CVE-2025-26427 is a powerful illustration of how path traversal bugs can open up severe privilege escalation: attackers can poke into other app spaces or sensitive system folders without explicit permission, simply by tricking users with a crafted input. Android’s fix is rolling out—make sure you’re patched, and if you write Android code, always sanitize your file paths!

Timeline

Published on: 09/04/2025 18:15:41 UTC
Last modified on: 09/05/2025 19:11:56 UTC