CVE-2026-53180 timers/migration: Fix livelock in tmigr_handle_remote_up()
A livelock in the Linux kernel timer migration code causes an infinite loop, leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-53180?
CVE-2026-53180 is a high-severity denial of service vulnerability in Linux kernel, published on 25 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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 ]
Which versions are affected by CVE-2026-53180?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53180?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-53180 being exploited?
There is no known exploitation of CVE-2026-53180 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-53180, DEBIAN-CVE-2026-53180, GHSA-gfr2-q5q8-v55v, UBUNTU-CVE-2026-53180.