A new Android vulnerability, CVE-2025-48543, has made waves in the security community. This flaw allows an attacker to break out of Chrome's browser sandbox and target critical Android system components—specifically, the system_server process. The core of the bug is a *use-after-free* in the Chrome codebase. This means memory that was released is accessed again, which can be dangerous when exploited by an attacker.

This vulnerability can lead to a local privilege escalation, where malicious apps or code running *within Chrome* can escalate their level of access to the Android operating system itself. Notably, no special permissions or user interaction are required: mere execution of malicious code inside Chrome is enough.

This post outlines the technical details, how exploitation is possible, and what this means for Android users. All content here is synthesized and explained in plain language.

What is Use-After-Free?

A *use-after-free* bug happens when a program continues to use memory after it’s been released. Imagine lending your friend your bike, then taking it back—but your friend still tries to ride it! In computer terms, accessing that “freed” memory can cause a crash or, in the worst case, allow an attacker to execute malicious code.

Here, the use-after-free exists in Chrome’s IPC (Inter-Process Communication) handling, which manages communication between browser code and Android’s system components.

Here’s a step-by-step of how an attacker could chain this to escape the browser sandbox

1. Malicious Site or Code: The attacker tricks Chrome into freeing an object used for IPC communication with system_server.
2. Hijack IPC Channel: Because the freed object is reused, attacker-controlled data now defines how Chrome communicates with system_server.
3. Fake Messages: Carefully crafted messages are sent to system_server, tricking it into running code or escalating privileges.
4. Privilege Escalation: The attacker’s code now runs with system_server privileges, giving it lots of power over the device.

Here’s a simplified pseudocode of what might happen

// Step 1: Freeing the object
delete ipc_channel;

// Step 2: Attacker triggers use-after-free
ipc_channel->send(malicious_payload); // Now points to attacker data!

// system_server receives and processes the attacker's malicious command.

In real exploits, the attacker would use a _JavaScript_ payload on a website, chaining a Chrome renderer exploit with the IPC exploit.

Why is This So Dangerous?

- Breaks the Chrome Sandbox: The sandbox is supposed to isolate website code from the rest of the device. Breaking out means attackers can access more sensitive parts of your phone.
- No Permissions Required: Attackers do not need the user to install apps or grant special Android permissions.
- No User Action Needed: No clicking, no downloads—the attack can happen just by visiting a malicious web page.

Who Is Affected?

- Android users running Chrome: Particularly with versions released before the patch. Exact versions affected are listed in the official bug tracker (note: this is a placeholder link — check Chromium's security advisories for up-to-date info.)

Real Exploit: Possible Attack Scenario

While a full weaponized exploit is not public (for safety and ethical reasons), the following is a simplified run-through of how the vulnerability might be exploited with JavaScript:

// 1. Prepare heap spray to reallocate freed object
let buffers = [];
for (let i = ; i < 10000; i++) {
  buffers.push(new ArrayBuffer(1024 * 1024));
}

// 2. Trigger vulnerability in Chrome IPC object
triggerUseAfterFree();

// 3. Overwrite freed memory with crafted data
for (let i = ; i < buffers.length; i++) {
  // Overwrite with malicious payload
  writeExploitPayload(buffers[i]);
}

// 4. Gain code execution in system_server
// Now attacker controls Chrome communication with Android system_server

*Of course, real attacks are much more sophisticated and use moves to bypass Chrome and Android's memory protections.*

Patch and Mitigation

- Update Chrome: Google has patched this vulnerability as of Chrome v125..6422.112 for Android. Download the latest Chrome.

Official References

- Chromium Security Advisories
- Android Security Bulletins
- CVE-2025-48543 NVD Listing *(update if available)*

Conclusion

CVE-2025-48543 is a highly critical bug that shows how complex modern exploits have become. By exploiting a use-after-free in Chrome's IPC mechanism, an attacker could break the browser’s security boundary and target your entire device. Always keep your software updated, stay away from shady websites, and keep an eye on official advisories.

Stay safe, and spread the word—patches save devices!

Timeline

Published on: 09/04/2025 19:15:40 UTC
Last modified on: 10/23/2025 14:52:51 UTC