# CVE-2026-98385: sched/cache: Decouple sched_cache_group from mm to fix UAF

> A use-after-free in the Linux kernel scheduler cache allows local attackers to execute arbitrary code or escalate privileges.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 12 Oct 2026
- **Updated:** 24 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-98385, GHSA-984h-v76f-94jc, UBUNTU-CVE-2026-98385

## What is CVE-2026-98385?

CVE-2026-98385 is a high-severity use after free vulnerability in Linux, published on 12 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/cache: Decouple sched_cache_group from mm to fix UAF

Currently the sched cache grouping is by mm and the scheduling statistics
sched_cache_stat lives in the mm structure.  This ties the life cycle
of scheduling stats with mm.

In account_mm_sched(), the scheduling stats are accessed by
task->mm->sc_stat.  However, a task may be switching mm on one CPU when
another CPU is running account_mm_sched(), and possibly accessing the
old mm that was freed.  This problem was found when running tests with
KASAN by Hyunwoo:

  https://lore.kernel.org/lkml/apPb-Dr4nPYuHQOK@v4bel/

Instead of serializing the mm access by introducing extra acquisition of
rq lock in the mm free path, extract sched_cache_stat from mm_struct,
rename it as sched_cache_group and manage its life cycle apart from
mm_struct with its own ref counting.  This allows us in the next patch
access sched_cache_group directly from task, and add a refcount
on sched_cache_group when a task links to it. This prevents the use
after free issue when accessing stale and released old mm and its
sched cache stat a task switches to a new mm while account_mm_sched()
is done elsewhere.

The other benefit of this restructure is in the future, the grouping of
tasks to a LLC would have the flexibility to be associated with a user
defined grouping, or cgroup, cookie group, numa_group or others instead
of just with a single mm address space.

Rename sched_cache_stat to sched_cache_group and turn it into a refcounted
object allocated from mm_struct.  The mm_struct now holds a pointer
(sched_cache_grp) to this object instead of embedding it.

## Which versions are affected by CVE-2026-98385?


## How do I fix CVE-2026-98385?

Apply the vendor's patch.

## Is CVE-2026-98385 being exploited?

There is no known exploitation of CVE-2026-98385 in the wild and no public exploit code.

Public exploit code:

- Android/ARM64 port (github_poc): https://github.com/ylh440104/InfinityCore-Android-CVE-2026-98385

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98385 and fix it if it is affected.

What it is: CVE-2026-98385 is a high-severity use after free vulnerability in Linux, published on 12 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-2026-98385 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-2026-98385/ (Markdown: https://insights.sbomify.com/CVE-2026-98385/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98385
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98385
- OSV: https://osv.dev/vulnerability/CVE-2026-98385

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98385/
Summaries are generated and may contain mistakes; the official description above is the record.