In June 2025, Apple patched a highly impactful use-after-free (UAF) vulnerability, tracked as CVE-2025-43529, across nearly its entire ecosystem. The bug was creepy, technical, and—most importantly—had already been used in the wild against select targets in a “highly sophisticated attack.” Below, we’ll break down what CVE-2025-43529 was, how attackers abused it, the patch, and what it means for you—plus code snippets that simplify what happened.

What? A use-after-free bug in Safari and Apple WebKit-based platforms.

- Where? Fixed in Safari 26.2, iOS/iPadOS 18.7.3 and 26.2, macOS Tahoe 26.2, and tvOS/visionOS/watchOS 26.2.

Risk? Code execution through malicious websites. Already used in real-world attacks.

- Reference? Apple Security Updates and National Vulnerability Database – CVE-2025-43529.

What is a Use-After-Free (UAF) Bug? (The Simple Version)

A use-after-free happens when a computer program hands memory back to the system (“frees” it) but then keeps using it (“uses after free”). That can mean reading old data—or, worse, attackers filling that space and sneaking in harmful instructions. When this occurs in a web browser like Safari, it’s a direct route for attackers to run code … just by tricking you into visiting a web page.

Think of it like throwing away your house key but still using it to unlock your door—eventually, someone could find it and open the door themselves.

Apple described this flaw as follows

> “A use-after-free issue was addressed with improved memory management. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been exploited in an extremely sophisticated attack against specific targeted individuals on versions of iOS before iOS 26.”
>
> — Apple Security Update, June 2025

Also see the NVD entry for CVE-2025-43529.

Where Did It Happen? (Affected Products)

Everything running WebKit:

Safari 26.2 and earlier

- iOS 18.7.3/26.2 and prior
- iPadOS 18.7.3/26.2 and prior

watchOS 26.2 and prior

If you hadn’t updated by June 2025, you were vulnerable.

How Do Attackers Exploit This Bug?

Attackers first create a maliciously crafted web page that exercises the use-after-free bug in WebKit’s memory management. Then, by carefully manipulating objects in memory, they can get the freed “house key” to point at their code, causing Safari (or any WebKit-based browser) to run it as if it were part of the browser itself.

*Visual: Simple Exploit Flow*

let victim = document.createElement('video');

// ... attacker triggers some bug that frees 'victim' but still uses it later

delete victim;

// Normally victim is gone, but attacker arranges...
playWithFreedPointer(victim); // The dangerous use-after-free

// Attacker then sprays memory with custom objects or shellcode
let array = [];
for (let i = ; i < 100000; i++) {
  array.push(new EvilObject());
}
// The browser can then execute arbitrary attacker's code

Note: The real exploit is more complex, but this snippet gives you a feel. The UAF lets an attacker control what code runs next.

Real-World Analogy

You’re told your hotel room key no longer works, but the key card machine at the bar still accepts it. If an attacker finds your thrown-away key, they can get into your room.

This vulnerability wasn’t a theoretical risk. Apple confirmed seeing it in the wild, writing

> “Apple is aware of a report that this issue may have been exploited in an extremely sophisticated attack against specific targeted individuals on versions of iOS before iOS 26.”

Translation: Hackers—likely with strong resources—used this zero-day against real people, probably in espionage or very high-stakes domains.

Additionally, CVE-2025-14174 was issued as a related response, also tied to these attacks.

The Fix

The solution? Improved memory management. Apple re-architected the way WebKit handles the recycling (“freeing”) and reuse of memory for certain objects so it won’t try to use data that’s already been given up. The bandaid: Always reference new objects and be sure nothing lingers after freeing.

You can see from the WebKit commit (not always public, but look for “use-after-free” in their changelogs) that these patches are deep under-the-hood and not something you, as a user, can patch yourself.

Mitigation: What Should You Do?

Update your Apple devices.

Additional Resources

- Apple Security Advisory for CVE-2025-43529
- NVD Entry for CVE-2025-43529
- Related: CVE-2025-14174
- WebKit Security Blog

For the security-curious, check out the WebKit bug tracker for future writeups.

Conclusion

CVE-2025-43529 is an example of how even small memory management bugs can have huge consequences—allowing attackers to breach the most locked-down Apple platforms out there. When bugs like these escape into the wild, patching fast is your best defense.

So: keep your Apple gear updated, always be cautious with web content, and if you’re in a high-risk group (journalists, activists, execs), never take a “no update” excuse lightly.

Timeline

Published on: 12/17/2025 20:46:55 UTC
Last modified on: 04/03/2026 14:17:40 UTC