# 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.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-98418, GHSA-2pjr-w693-xmqc, UBUNTU-CVE-2026-98418

## 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.

## Is CVE-2026-98418 being exploited?

There is no known exploitation of CVE-2026-98418 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98418 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-98418 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-98418/ (Markdown: https://insights.sbomify.com/CVE-2026-98418/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98418
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98418
- OSV: https://osv.dev/vulnerability/CVE-2026-98418

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98418/
Summaries are generated and may contain mistakes; the official description above is the record.