Single Line of Code iPhone Exploit: Critical Vulnerability Could Brick Devices

A security researcher has uncovered a critical vulnerability in iOS that allows any app to potentially “brick” an iPhone using just a single line of code. This discovery highlights a significant security blind spot in Apple’s operating system that could have devastating consequences for affected users.

 Description of the Vulnerability

The vulnerability, tracked as CVE-2025-24091, leverages the little-known “Darwin notification” system deeply embedded within Apple’s CoreOS layer. This legacy API, which has been part of iOS for years, allows for low-level messaging across process boundaries without requiring special privileges.

Darwin notifications provide a low-level mechanism for simple message exchange between processes on Apple’s operating systems. While most iOS developers are familiar with NSNotificationCenter for intra-app communication, Darwin notifications enable system-wide messaging that can cross process boundaries—meaning virtually any app, even those restricted by Apple’s sandbox, can send these signals.

The critical security flaw in this system is the complete lack of sender verification or privilege gating. Any app can send Darwin notifications that were originally intended only for system components, potentially triggering powerful operations that should be restricted.

 Severity of the Issue

This vulnerability is particularly severe because it can cause permanent denial of service with minimal effort. The exploit allows any app, including those confined by Apple’s usually strict sandbox restrictions, to push the entire device into an inescapable “restore in progress” state with a single line of code.

The worst implementation of this exploit leverages iOS’s widget extension framework to create an endless boot loop:

1. A malicious app sends a Darwin notification that triggers a fake “restore in progress” state
2. When embedded in a widget extension, this code runs at system startup—even before a device is fully unlocked
3. The device crashes and reboots due to the notification
4. Upon reboot, the widget extension runs immediately, triggering the exploit again
5. This creates an inescapable cycle, effectively “soft-bricking” the device

The only solution for affected users is a complete device erase and restore from backup. However, if the infected app is included in the backup, the cycle can begin again, leading to a persistent denial of service.

 How the Exploit Works

The exploit works by abusing legitimate system-wide notifications that are normally used for internal iOS functions. The researcher who discovered this vulnerability created a proof-of-concept app called “EvilNotify” that demonstrated several attack vectors.

The most devastating implementation sends a notification that tricks the system into believing a device restore is in progress. This triggers iOS’s built-in restore mode UI, which locks the user out of normal device functionality. By combining this with widget extensions that run at startup, the device becomes trapped in an endless loop of crashes and reboots.

The fundamental issue is that Apple’s Darwin notification system, designed decades ago for benign system communication, lacks proper access control or sender authentication. What was once a convenient internal messaging system has now become a serious security vulnerability that exposes the entire device to potential attack.

 Who is Behind the Discovery

The vulnerability was discovered by a security researcher who specializes in iOS security. Upon confirming the exploit’s effectiveness, the researcher responsibly disclosed the vulnerability to Apple through their security vulnerability reporting program.

The researcher followed responsible disclosure protocols, providing Apple time to address the vulnerability before publicly revealing the details. This approach helps protect users by giving the vendor an opportunity to develop and release a fix before potential attackers can exploit the vulnerability.

 Who is at Risk

All iPhone users running vulnerable versions of iOS are potentially at risk from this exploit. The vulnerability affects a wide range of iOS versions, as the Darwin notification system is a long-standing component of the operating system.

Users are particularly vulnerable if they:

1. Install apps from unfamiliar or untrusted sources
2. Use beta versions of iOS on their primary devices
3. Jailbreak their devices, which circumvents Apple’s App Store review process

The risk is higher for users who might be specifically targeted, such as those in positions with access to sensitive information or high-value individuals who might be worth the effort of a targeted attack.

 Recommended Remediations

While Apple works on a permanent fix for this vulnerability, users can take several precautions to protect themselves:

1. Install iOS updates promptly: Apple is expected to release a patch addressing this vulnerability in an upcoming iOS update. Install security updates as soon as they become available.
2. Exercise caution with app installations: Only download apps from the official App Store, and be wary of new or unfamiliar developers.
3. Review app permissions: Be mindful of the permissions you grant to apps, especially newer or less established applications.
4. Avoid beta software on critical devices: If you need to test beta versions of iOS, do so on secondary devices rather than your primary phone.
5. Maintain regular backups: Ensure you have recent backups of your device stored in multiple locations (both iCloud and local computer backups).
6. Consider endpoint protection: For business environments, consider mobile device management (MDM) solutions that can help detect and prevent malicious app behavior.

According to the researcher, Apple’s mitigation involves requiring restricted entitlements for sending sensitive Darwin notifications. The first adopters were backupd, BackupAgent2, and UserEventAgent, all gaining entitlements related to notifying the system about device restores.

How CinchOps Can Help Secure Your Business

At CinchOps, we understand the serious implications of mobile device vulnerabilities for businesses. Our cybersecurity services can help protect your organization from threats like the Darwin notification exploit:

1. Mobile Device Management: We implement comprehensive MDM solutions that provide visibility and control over all mobile devices in your organization.
2. Security Policy Development: We help create and enforce security policies that restrict app installations to trusted sources and require security reviews for business applications.
3. Vulnerability Monitoring: Our services include continuous monitoring for new vulnerabilities affecting your mobile fleet, ensuring prompt response when issues are discovered.
4. Patch Management: We help manage the deployment of security updates across your organization’s devices to ensure vulnerabilities are addressed promptly.
5. Security Awareness Training: We train your employees to recognize potential mobile threats and follow best practices for device security.
6. Incident Response Planning: In the event a device is compromised, we help develop and implement response plans to minimize impact and restore functionality.

This vulnerability serves as a reminder that even seemingly simple APIs can create significant security risks when they lack proper access controls. As mobile devices continue to store and process increasingly sensitive data, maintaining their security becomes ever more critical.

Don’t wait until your organization experiences a mobile security incident. Contact CinchOps today to learn how our comprehensive cybersecurity services can help protect your business mobile devices from emerging threats.

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For Additional Information on this topic: New iOS Vulnerability Could Brick iPhones with Just One Line of Code

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