Critical iOS Vulnerability Discovered: A Single Line of Code Can Brick iPhones

In today’s world, smartphones have become an indispensable part of our lives. They are not just communication tools but also central hubs for our personal data, financial transactions, and core business processes. However, no matter how advanced these devices are, vulnerabilities in their operating systems can open the door for cybercriminals. A recently discovered vulnerability in iOS, identified as CVE-2025-24091, is one such dangerous case. This flaw allows a single line of code to render iPhone and iPad devices completely inoperable—effectively “bricking” them.

Apple’s iOS operating system is renowned for its robustness and security, but outdated APIs in its lower-level layers can sometimes conceal dangerous gaps. The CVE-2025-24091 vulnerability was found in a mechanism known as the Darwin Notifications system, located in the core layer of Apple’s operating system, CoreOS. This system enables simple, system-wide message exchanges between processes.

According to researcher Guilherme Rambo, “Unlike systems like NSNotificationCenter or NSDistributedNotificationCenter, Darwin notifications are a much simpler, low-level mechanism. They are used for message exchanges between processes in Apple’s operating systems.” However, this simplicity led to a critical flaw: any iOS application could send sensitive system-level Darwin notifications without requiring special permissions (entitlements). Most alarmingly, these notifications could trigger critical system functions, such as entering a “Restore in Progress” mode.

Exploiting this vulnerability is astonishingly simple: just one line of code can render a device unusable. The researcher developed a proof-of-concept attack called VeryEvilNotify, embedding the code within a widget extension. The code operates as follows:

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// Sample malicious code (generalized for security purposes) notify_post("com.apple.mobile.softwareupdated.restore");

This code forcibly puts the device into a “Restore in Progress” state. Since no actual restoration process is occurring, the system fails, prompting the user to restart the device. Because widget extensions are periodically activated in the background by iOS, the malicious code re-executes after each reboot, trapping the device in an endless reboot loop. As a result, the device becomes completely inoperable and can only be restored through a full system reinstallation.

The researcher noted, “Widget extensions are widely used in the system, so when a new app with a widget extension is installed or launched, iOS is eager to activate the widget. This enables the automatic execution of malicious code.”

The key dangers of this vulnerability include:

  • Affected Devices: All iPhones and iPads running iOS versions prior to 18.3.
  • Impact Type: Denial of Service (DoS), rendering the device completely unusable.
  • Exploitation Conditions: Any sandboxed app or widget extension can trigger the vulnerability without special permissions.
  • CVSS 3.1 Rating: High (critical threat level).

The most concerning aspect is that the vulnerability can be exploited through seemingly innocent apps distributed via the App Store or other channels. For example, malicious code could be hidden in a gaming app or a social media widget.

Apple addressed this vulnerability in iOS 18.3 by introducing a new permission system for critical Darwin notifications. Now, such notifications must use the com.apple.private.restrict-post. prefix, and the sending process must have specific entitlements in the format com.apple.private.darwin-notification.restrict-post.<notification>.

Researcher Guilherme Rambo was awarded $17,500 by Apple for discovering this vulnerability, highlighting the company’s commitment to collaborating with security researchers.

This is not the first Darwin-related vulnerability in Apple’s systems. Previously, Kaspersky Lab identified the Darwin Nuke vulnerability, which allowed remote attackers to launch denial-of-service attacks using specially crafted network packets. This case underscores the need for continuous scrutiny of outdated APIs to ensure security.

All iPhone and iPad users are urgently recommended to update to iOS 18.3 or later immediately. Devices running earlier versions remain vulnerable to this attack. The update process is straightforward and involves the following steps:

  1. Open the Settings app.
  2. Navigate to General → Software Update.
  3. Download and install iOS 18.3 or a later version.

Additionally, users are advised to take the following precautions:

  • Avoid Untrusted Apps: Install only verified apps from the App Store and avoid downloading software from unknown sources.
  • Choose Widgets Carefully: Widgets often run in the background and can covertly activate malicious code.
  • Monitor System Behavior: If your device experiences unusual reboots or errors, contact Apple Support immediately.

In Uzbekistan, the number of iPhone users is steadily growing, particularly among youth and business professionals. This vulnerability poses a significant threat to Uzbekistani users as well, given that cybercriminals operate globally. The following additional measures are particularly relevant in the local context:

  • Verify Local Apps: When installing apps developed or distributed in Uzbekistan, ensure their reliability. Avoid unknown apps or widgets shared via Telegram.
  • Stay Informed About Cybersecurity: Follow cybersecurity updates in Uzbek through Telegram channels (e.g., using hashtags like #KiberXavfsizlik or #XavfsizInternet).
  • Maintain Backups: Regularly back up your data via iCloud or a computer. This will aid in data recovery if your device becomes inoperable.

This vulnerability highlights ongoing security challenges in mobile operating systems that demand constant vigilance. Even giants like Apple can be susceptible due to outdated APIs or misconfigurations. This case serves as a warning for both users and software developers.

In Uzbekistan’s rapidly evolving IT market, such vulnerabilities underscore the need to foster a cybersecurity culture. Local companies and users can protect themselves by promptly installing security updates, avoiding suspicious apps, and enhancing their cybersecurity knowledge.

The CVE-2025-24091 vulnerability exposed a serious gap in iOS device security. The ability to brick a device with a single line of code is a stark reminder of the need for continuous vigilance in cybersecurity. While Apple resolved the issue in iOS 18.3, users must update their devices and adopt precautions to ensure their security.

Cybersecurity is not just a technical issue but a responsibility for every user. Creating a secure digital environment in Uzbekistan and worldwide requires knowledge, caution, and swift action. If you have further questions or need advice on strengthening iOS security, feel free to reach out—I’ll explain each step in detail!