# CVE-2026-98446: xfs: don't let hidden_space go negative in xfs_metafile_resv_init

> An integer underflow in the Linux kernel XFS filesystem can cause excessive space reservation, leading to a 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:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-98446, DEBIAN-CVE-2026-98446, GHSA-8r8r-jgjj-w55r, UBUNTU-CVE-2026-98446

## What is CVE-2026-98446?

CVE-2026-98446 is a vulnerability in Linux, published on 18 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:

xfs: don't let hidden_space go negative in xfs_metafile_resv_init

LOLLM points out that if the amount of fdblocks that we can reserve for
a metadata btree file goes below the space already used by that file,
then the hidden_space subtraction can underflow, causing
xfs_dec_fdblocks to subtract a huge amount of space.  We never want the
target to be less than the used sapce, so fix the logic that adjusts
dblocks_avail downwards.

Also fix an error in the adjacent comment.

## Which versions are affected by CVE-2026-98446?


## How do I fix CVE-2026-98446?

Apply the vendor's patch.

## Is CVE-2026-98446 being exploited?

There is no known exploitation of CVE-2026-98446 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98446 and fix it if it is affected.

What it is: CVE-2026-98446 is a vulnerability in Linux, published on 18 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-2026-98446 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-2026-98446/ (Markdown: https://insights.sbomify.com/CVE-2026-98446/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98446
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98446
- OSV: https://osv.dev/vulnerability/CVE-2026-98446

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98446/
Summaries are generated and may contain mistakes; the official description above is the record.