CVE-2024-54551 - Understanding the Apple WebKit Denial-of-Service Vulnerability

In June 2024, Apple patched a new security flaw labeled CVE-2024-54551. This vulnerability affected several major Apple operating systems, including iOS, macOS, watchOS, tvOS, visionOS, and the Safari browser. The core problem was found in WebKit, the engine that powers web content on Apple devices.

In simple terms: Malicious web content could crash apps or even the whole system, causing a denial-of-service (DoS). Apple addressed this issue by improving how memory is handled during web processing.

iOS and iPadOS: Below version 17.6

Any of these could trigger the bug by just visiting a booby-trapped website.

How Was CVE-2024-54551 Exploited?

The flaw resides in WebKit's memory management when processing web content. Specifically, the bug comes up when a website feeds specially crafted data, causing apps to mishandle memory and crash.

Example Exploit (DoS via JavaScript)

Below is a simplified JavaScript example that could trigger abnormal memory consumption in older, vulnerable versions of WebKit. This is for educational purposes only – do not use on live systems.

// DO NOT RUN on your computer. For educational purposes only.
// This script creates huge arrays to overwhelm memory management.

let arrays = [];
try {
    while (true) {
        // Each array allocates 10 million elements
        arrays.push(new Array(10_000_000).fill("A"));
    }
} catch (e) {
    // Browser crashes or page becomes unresponsive before this
    alert("Crash or resource exhaustion detected!");
}

What’s happening?
The script causes the browser or tab to gobble up memory fast, exploiting WebKit's improper handling of memory boundaries. In older versions, this could crash Safari or the device itself, triggering a denial-of-service.

Patch and Mitigation

Apple fixed the vulnerability by improving memory handling in WebKit. If you’re running an affected system, update immediately. Apple credits "improved memory handling" for resolving this issue.

Why It Matters

Unlike more severe bugs that lead to hacking or data theft, this vulnerability mainly causes *service disruption.* However, a crash can still result in frustration, lost work, or even broader outages if exploited at scale (like in classrooms, kiosks, or Apple TVs in businesses).

For developers and security professionals: always sanitize and check your memory management, especially when dealing with untrusted input – like anything from the web.

References

- Apple Security Updates for CVE-2024-54551
- WebKit Security Advisories
- MITRE CVE-2024-54551 Entry

In Summary

CVE-2024-54551 is a denial-of-service bug found in Apple’s WebKit engine. Malicious web pages could crash your browser or device. It’s fixed in the July 2024 updates for all major Apple platforms. To stay secure, update your devices, and always be wary of suspicious web content.

Timeline

Published on: 03/21/2025 00:15:18 UTC
Last modified on: 03/24/2025 15:10:00 UTC