CVE-2024-47671

What it actually does

The usbtmc_write function in the Linux kernel USB TMC driver fails to clear a structure before populating fields, resulting in uninitialized kernel memory being copied to a USB device and causing an information disclosure.

Why it matters to the business

Kernel memory contents that may include sensitive data such as credentials or internal state can be leaked to an attached USB device, increasing exposure risk across Linux-based systems that use the usbtmc driver.

How an attack unfolds

An attacker with physical or logical access to a USB device connected to a vulnerable Linux system triggers the usbtmc_write path; because the structure is not zeroed, residual kernel memory is transmitted over USB, allowing the attacker to capture the leaked data. The issue appears in zero-day exploitation campaigns and has been referenced in broader Linux kernel uninitialized resource and out-of-bounds access discussions.

How to fix it

Update the Linux kernel to the commit fa652318887da530f2f9dbd9b0ea4a087d05ee12 or a later stable release that includes the fix; rebuild and deploy the patched kernel across affected systems.

How to confirm the fix worked

Confirm the running kernel contains commit fa652318887da530f2f9dbd9b0ea4a087d05ee12 or verify that usbtmc_write properly clears the structure before use; test with the original syzbot reproducer to ensure no leakage occurs.

Typical attack path

1. Obtain physical or logical access to a USB device attached to a target Linux system
2. Issue a write operation that reaches the usbtmc_write handler
3. Read the unintended kernel memory that is transmitted due to the uninitialized structure
4. Exfiltrate captured data for further analysis or credential harvesting

How to detect it

Review kernel logs and USB trace data for unexpected or oversized transfers originating from the usbtmc driver; correlate with process activity that opens usbtmc character devices.

What your security team should do

• Apply the kernel patch containing commit fa652318887da530f2f9dbd9b0ea4a087d05ee12 immediately on all systems using the usbtmc driver
• Limit physical USB access and enforce device allow-listing where possible
• Monitor for kernel updates in the stable tree and schedule rolling deployments
• Review USB-related drivers for similar uninitialized memory patterns