CVE-2026-98418 sched/core: Avoid false migration warning for proxy donors
A local attacker can trigger a kernel warning and potential instability by exploiting false migration warnings in the Linux kernel scheduler.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98418?
CVE-2026-98418 is a denial of service vulnerability in Linux, published on 14 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
sched/core: Avoid false migration warning for proxy donors
Proxy execution can move a blocked donor's scheduling context to the lock owner's CPU even when the donor is migration-disabled. The donor does not execute there, and its original execution CPU remains recorded in wake_cpu.
set_task_cpu() warns unconditionally for migration-disabled tasks, so a subsequent proxy migration or the wakeup path returning the donor home triggers a false positive: moving a blocked scheduling context does not violate the migration-disabled execution context.
For example, creating a mutex owner on CPU1 and a migration-disabled waiter on CPU0 can trigger the following warning:
proxy_migrate_repro: donor blocking on CPU0 with migration disabled proxy_migrate_repro: donor moved from CPU0 to CPU1 WARNING: kernel/sched/core.c:3389 at set_task_cpu+0x1d3/0x280 ... Call Trace: try_to_wake_up+0x43f/0x780 __mutex_unlock_slowpath+0x330/0x540 owner_fn+0x9f/0xc0 [proxy_migrate_repro] ... proxy_migrate_repro: donor woke on CPU0, task_cpu=0 proxy_migrate_repro: completed
Exclude blocked proxy donors from the warning. The proxy wakeup path restores an executable placement before clearing the blocked state.
Which versions are affected by CVE-2026-98418?
How do I fix CVE-2026-98418?
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-2026-98418 being exploited?
There is no known exploitation of CVE-2026-98418 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-98418, GHSA-2pjr-w693-xmqc, UBUNTU-CVE-2026-98418.