CVE-2026-43385 is a high-severity vulnerability in the Linux kernel related to a stall in the rcu_tasks grace period when using threaded busypoll in network device drivers. The issue causes the system to hang due to improper handling of the last quiescent state timestamp in the polling loop, leading to rcu_tasks stalls and potential denial of service. The vulnerability was fixed by adjusting how the last quiescent state is tracked in the threaded busypoll implementation.