# CVE-2026-93229: nfsd: add missing read barrier to rpc_status_get dumpit seqcount retry

> A missing memory barrier in the Linux kernel NFS server allows concurrent data modification to be observed inconsistently, potentially leading to incorrect data reads.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-93229, DEBIAN-CVE-2026-93229, GHSA-fg62-2q3c-3w5h, UBUNTU-CVE-2026-93229

## What is CVE-2026-93229?

CVE-2026-93229 is a high-severity 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:

nfsd: add missing read barrier to rpc_status_get dumpit seqcount retry

The hand-rolled seqcount-like protocol in nfsd_nl_rpc_status_get_dumpit()
is missing a read memory barrier (smp_rmb) before its second counter
check.  The standard kernel read_seqcount_retry() includes smp_rmb()
to ensure that all data reads complete before the counter is re-checked.

Without this barrier, on weakly-ordered architectures (ARM, POWER),
the CPU may reorder field reads past the second counter check, making
the retry logic ineffective: it could observe a consistent counter pair
while reading fields that have been concurrently modified by the writer.

Add smp_rmb() before the second counter check to order the field reads
ahead of it, matching the barrier semantics of the standard seqcount
read-side.  The begin-side smp_load_acquire() already pairs with the
smp_store_release() in nfsd_dispatch(); with the smp_rmb() now ordering
the field reads, the retry check no longer needs acquire semantics and
reads the counter with a plain READ_ONCE(), as read_seqcount_retry()
does.

[ cel: Use READ_ONCE instead of smp_load_acquire() ]

## Which versions are affected by CVE-2026-93229?


## How do I fix CVE-2026-93229?

Apply the vendor's patch.

## Is CVE-2026-93229 being exploited?

There is no known exploitation of CVE-2026-93229 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93229 and fix it if it is affected.

What it is: CVE-2026-93229 is a high-severity 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-2026-93229 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-2026-93229/ (Markdown: https://insights.sbomify.com/CVE-2026-93229/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93229
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93229
- OSV: https://osv.dev/vulnerability/CVE-2026-93229

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93229/
Summaries are generated and may contain mistakes; the official description above is the record.