CVE-2026-53180
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk37th percentile — higher than 37% of all known CVEs
Summary
A livelock vulnerability was found in the Linux kernel's timer migration mechanism in the tmigr_handle_remote_up() function. The issue stems from an incorrect assumption that the local softirq already handled the CPU's timers, causing timer_expire_remote() to be skipped and leading to an infinite loop.
Risk Assessment
This vulnerability can cause a system livelock, rendering the system unresponsive and posing a significant risk to system availability.
Recommendation
Immediately update the Linux kernel to a version containing the fix that unconditionally calls timer_expire_remote() instead of skipping it conditionally.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: timers/migration: Fix livelock in tmigr_handle_remote_up() tmigr_handle_remote_cpu() skips timer_expire_remote() when cpu == smp_processor_id(), assuming the local softirq path already handled this CPU's timers. This assumption is wrong because jiffies can advance after the handling of the CPU's global timers in run_timer_base(BASE_GLOBAL) and before tmigr_handle_remote() evaluates the expiry times. As a consequence a timer which expires after the CPU local timer wheel advanced and becomes expired in the remote handling is ignored and the callback is never invoked and removed from the timer wheel. What's worse is that fetch_next_timer_interrupt_remote() keeps reporting it as expired, and the event is re-queued with expires == now on each iteration. The goto-again loop spins indefinitely. Fix this by calling timer_expire_remote() unconditionally. That's minimal overhead for the common case as __run_timer_base() returns immediately if there is nothing to expire in the local wheel. [ tglx: Amend change log and add a comment ]