CVE-2026-63930 addresses a use-after-free vulnerability in the Linux kernel's IIO buffer hardware consumer code. Specifically, during error cleanup in iio_hw_consumer_alloc(), the code used list_for_each_entry() to iterate over buffers while calling iio_buffer_put(), which can free the current buffer if its reference count drops to zero. The iteration macro then accessed the freed buffer's next pointer, causing a use-after-free. The vulnerability was fixed by switching to list_for_each_entry_safe(), which safely handles element removal during iteration.

The vulnerability could cause the kernel to access freed memory during error handling, potentially leading to kernel crashes, memory corruption, or undefined behavior. No known exploits in the wild have been reported. The impact is limited to affected kernel versions and occurs in the Industrial I/O subsystem during error cleanup.

A fix is available and has been applied to the Linux kernel source code by replacing the unsafe list iteration macro with a safe variant. Users should update their Linux kernel to a version that includes this fix. Since no specific patched versions are provided, check the official Linux kernel advisories or source repositories for the fixed commit.