---

What is CVE-2025-0077?

*CVE-2025-0077* is a newly discovered vulnerability affecting systems where the UserController.java file is used to manage user sessions and lock screen mechanisms. This vulnerability arises from a race condition, which can allow a local attacker to bypass the lock screen and escalate privileges without any user interaction.

In simple terms, due to how multiple functions in UserController.java interact and manage user state, a carefully timed attack can force the system to unlock the screen even when it shouldn’t, giving unauthorized access to sensitive data and features.

> TL;DR: CVE-2025-0077 lets a local user bypass the lock screen, becoming a serious security risk for devices relying on this code.

Why This Vulnerability Matters

A race condition occurs when two or more processes (or threads) access shared data at the same time, leading to unexpected results. In the case of UserController.java, this race can be exploited so that a user can get past the lock screen just by hitting the right code path at the right moment – no passwords, pins, or biometrics needed.

Vulnerable systems

- Devices or apps using the susceptible version of UserController.java for user management and lock screens.

Let’s look at an example, simplifying how the issue might look in Java

// UserController.java (vulnerable pseudocode example)
public class UserController {
    private boolean isLocked = true;

    public void lockScreen() {
        isLocked = true;
    }

    public void unlockScreen(String password) {
        if (validatePassword(password)) {
            isLocked = false;
        }
    }

    // Suppose this function is called during some system process
    public void handleUserSession() {
        if (!isLocked) {
            // Let user access the session
            grantAccess();
        } else {
            // Show lock screen
            showLockScreen();
        }
    }
}

Where’s the problem?
Let’s say unlockScreen() and handleUserSession() can be called on different threads almost at the same time. If an attacker can trigger handleUserSession() continuously while racing with a fake or empty password given to unlockScreen(), sometimes the isLocked value may not be properly updated before access is granted.

Attacker triggers unlockScreen("wrong") at the same time as handleUserSession().

2. Through timing, the system may read isLocked as false before the validation completes, letting the attacker in.

Device is locked.

2. Attacker writes a script or uses a custom app to flood handleUserSession() calls while alternating password attempts (even with empty or wrong passwords).
3. Eventually, due to race conditions, the lock state reads as (isLocked == false) just as handleUserSession() grants access.

The lock screen disappears, and the attacker gets access to the owner’s session.

No interaction needed: The attack is fully automated and does not rely on user mistakes. No extra permissions are required – just local app or script execution.

- NIST National Vulnerability Database - CVE-2025-0077
- Common Weakness Enumeration: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization - Race Condition)
- Race Condition Explained (OWASP)

Here’s a proof-of-concept in Java pseudocode to show how the attack might work

public class RaceBypassDemo {
    static UserController userController = new UserController();

    public static void main(String[] args) {
        // Lock the screen
        userController.lockScreen();

        // Thread 1: tries to unlock with a wrong password in a loop
        Thread t1 = new Thread(() -> {
            while (true) {
                userController.unlockScreen("wrongpassword");
            }
        });

        // Thread 2: tries to access user session in a loop
        Thread t2 = new Thread(() -> {
            while (true) {
                userController.handleUserSession();
            }
        });

        t1.start();
        t2.start();
    }
}

*On some vulnerable systems, this kind of attack can time things just right to break in.*

Mitigation Tips

- Use proper synchronization (like synchronized blocks or mutexes) for any shared variables like isLocked.

Consider redesigning the session and lock state management to avoid race windows.

// Safer approach with synchronized keyword
public synchronized void unlockScreen(String password) { ... }

public synchronized void handleUserSession() { ... }

Final Thoughts

*This vulnerability highlights why concurrent programming bugs are so dangerous on user-facing, security-critical code like lock screens. With just a bit of local access and no fancy privileges, attackers can take over locked sessions by exploiting subtle race conditions.*

If your system, app, or device uses UserController.java in a similar fashion, patch immediately. Synchronized code is a must, especially for anything that protects user privacy or device security.

Stay up to date on the CVE:
- CVE-2025-0077 at MITRE
- NIST NVD Entry


*Always patch early and audit your code for race conditions. Simple bugs can have big impacts!*

Timeline

Published on: 09/04/2025 18:15:38 UTC
Last modified on: 09/05/2025 18:57:56 UTC