# CVE-2026-97534: f2fs: accurately adjust free_sections during free_segment_range

> A logic error in the Linux kernel's f2fs filesystem can cause allocation failures and assertion errors, leading to denial of service.

- **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:** 25 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-104532, BELL-CVE-2026-97534, DEBIAN-CVE-2026-97534, GHSA-9m8h-hg7g-4xp7, UBUNTU-CVE-2026-97534

## What is CVE-2026-97534?

CVE-2026-97534 is a denial of service vulnerability in Linux, published on 25 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:

f2fs: accurately adjust free_sections during free_segment_range

In free_segment_range(), MAIN_SECS(sbi) is temporarily reduced by `secs`
to restrict block allocation to the safe remaining main area while valid
blocks in the truncated range are evacuated by GC.

However, FREE_I(sbi)->free_sections tracks the total number of free
sections across the whole filesystem. If any sections within the
truncated range were already free upon entering free_segment_range(),
failing to deduct them from free_sections causes the filesystem to
overestimate available free sections in the active, reduced main area.
This leads to inconsistent free section accounting during GC data
migration and can trigger unexpected allocation failures or assertion
errors when space is tight.

Fix this by calculating the number of already-free sections in the
truncated range, deducting them from free_sections upon entering
free_segment_range(), and restoring them on exit.

## Which versions are affected by CVE-2026-97534?


## How do I fix CVE-2026-97534?

Apply the vendor's patch.

## Is CVE-2026-97534 being exploited?

There is no known exploitation of CVE-2026-97534 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97534 and fix it if it is affected.

What it is: CVE-2026-97534 is a denial of service vulnerability in Linux, published on 25 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-2026-97534 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-2026-97534/ (Markdown: https://insights.sbomify.com/CVE-2026-97534/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97534
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97534
- OSV: https://osv.dev/vulnerability/CVE-2026-97534

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97534/
Summaries are generated and may contain mistakes; the official description above is the record.