# CVE-2026-93240: memcg: make the v1 soft limit knob inert

> A kernel bug in memory cgroup soft limit handling could cause a warning or instability when triggered by privileged users, requiring a patch to stabilize the system.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-103559, BELL-CVE-2026-93240, DEBIAN-CVE-2026-93240, GHSA-xfgg-2xcm-vrc8, UBUNTU-CVE-2026-93240

## What is CVE-2026-93240?

CVE-2026-93240 is a denial of service vulnerability in Linux, published on 24 Sep 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:

memcg: make the v1 soft limit knob inert

The v1 soft limit has been deprecated since v6.12 and nobody has reported
depending on it.  Start the removal by decoupling the interface from the
implementation: keep memory.soft_limit_in_bytes, but ignore writes to it
and always report the maximum value on read similar to what
memory.kmem.limit_in_bytes already does.

Writes are still parsed, so malformed input keeps returning -EINVAL.  The
knob now also behaves the same everywhere: it used to return -EOPNOTSUPP
on PREEMPT_RT, where soft limit reclaim has always been disabled.

This also fixes the syzbot report linked below.  Soft limit reclaim is the
only caller that runs shrink_lruvec() from kswapd against a specific
memcg, so it is the only way to reach lru_gen_shrink_lruvec() and in turn
set_mm_walk(), which warns when called from kswapd.

## Which versions are affected by CVE-2026-93240?


## How do I fix CVE-2026-93240?

Apply the vendor's patch.

## Is CVE-2026-93240 being exploited?

There is no known exploitation of CVE-2026-93240 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93240 and fix it if it is affected.

What it is: CVE-2026-93240 is a denial of service vulnerability in Linux, published on 24 Sep 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-2026-93240 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-2026-93240/ (Markdown: https://insights.sbomify.com/CVE-2026-93240/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93240
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93240
- OSV: https://osv.dev/vulnerability/CVE-2026-93240

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93240/
Summaries are generated and may contain mistakes; the official description above is the record.