In June 2024, Apple fixed a critical use-after-free (UAF) vulnerability registered as CVE-2025-24252 across several of its platforms. This bug affected a broad swath of Apple operating systems, including macOS Sequoia 15.4, tvOS 18.4, macOS Ventura 13.7.5, iPadOS 17.7.6, macOS Sonoma 14.7.5, iOS 18.4, iPadOS 18.4, and visionOS 2.4. In this article, we’ll break down what went wrong, how an attacker could exploit this UAF to corrupt process memory, and how the patch closes the door on this risk. Let’s dig in!

What is a Use-After-Free Issue?

A *use-after-free* (UAF) happens when an application continues to use a piece of memory after it has been returned to the operating system. This creates a condition where bad actors can insert their own data, or manipulate system data, by controlling what happens to that freed block of memory.

Take this simplified C++-like scenario

class NetworkObject {
    public:
        void sendPacket();
};

void processConnection() {
    NetworkObject* obj = new NetworkObject();
    obj->sendPacket();
    delete obj;

    // Unsafe: obj has already been deleted!
    obj->sendPacket();
}

Here, calling sendPacket() after delete obj is a classic UAF bug.

Where Did This Happen?

Apple's own advisory (Apple Security Updates) says only that the bug affected the operating systems listed above. The root problem was memory management in a part of the network stack, accessible to some extent by *local network* attackers (e.g., someone on your Wi-Fi or LAN).

Why is this dangerous?
If an attacker can trigger the use-after-free and reliably time allocation of other data structures after the free, they can corrupt memory used by critical processes. This can lead to crashes, privilege escalation, or even arbitrary code execution.

Exploit Details (Simplified)

The details behind Apple’s network stack are not public, but we can outline a generalized path of exploitation:

Trigger Free: The attacker sends crafted network traffic.

2. Force Use-After-Free: The system frees the memory but soon tries to use it again, possibly as a network object or buffer.
3. Heap Spraying (Attacker-controlled allocation): The attacker floods the target with packets, hoping to allocate their controlled data exactly where the freed memory used to be.
4. Corrupt Process Memory: When the system tries to use what it thinks is a valid structure, it operates on the attacker’s data instead.

Suppose the issue affected a C-like structure for a network service

typedef struct {
    char *username;
    int session_id;
} user_session;

void close_connection(user_session *session) {
    free(session);
    // ...more network activity...
    // Oops, session is used again
    send_session_data(session);
}

An attacker who can trigger close_connection() at the right moment could take control of the session pointer’s data, thus affecting sensitive process memory.

Patch, Fix & Safety

With the updates mentioned, Apple hardened memory management in the affected code. Instead of simply freeing and possibly re-using pointers, Apple now guarantees all references are cleared before freeing, and double-checks pointer states before use.

From Apple’s notes

> “A use-after-free issue was addressed with improved memory management.”
> — Apple Security Updates

Cleaned up Example

void close_connection(user_session **session) {
    free(*session);
    *session = NULL; // prevents further accidental use
    // no further access to *session here!
}

Who Needs to Worry?

If your device runs any of these systems and is on a network with possible attackers (e.g., public Wi-Fi, shared LAN), you should update immediately. While there’s no public exploit code yet, local network bugs have historically become serious threats if left unpatched.

Summary

- CVE-2025-24252 is a major use-after-free memory bug in Apple’s operating systems, with the potential for process memory corruption via the local network.

The fix uses better memory management, specifically avoiding continued usage of freed memory.

- This is a reminder to always keep your devices up-to-date, particularly if you’re on networks you don’t fully control.

References

- Apple Security Updates - June 2024
- Wikipedia: Use-after-free
- Common Weakness Enumeration: CWE-416

Timeline

Published on: 04/29/2025 03:15:34 UTC
Last modified on: 04/29/2025 20:10:47 UTC