# CVE-2026-90102: NFSv4/pnfs: key the data server cache on the NFS version

> A null pointer dereference in the Linux kernel NFSv4/pnfs module can cause a denial of service when data servers with different NFS versions share an address.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-101861, BELL-CVE-2026-90102, DEBIAN-CVE-2026-90102, GHSA-wj5v-2g3c-hmrh, UBUNTU-CVE-2026-90102

## What is CVE-2026-90102?

CVE-2026-90102 is a high-severity vulnerability in Linux, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

NFSv4/pnfs: key the data server cache on the NFS version

nfs4_pnfs_ds_add() keys the per-net data server cache on the multipath
address set alone, and struct nfs4_pnfs_ds records no version. That
suffices for the files layout driver, which always connects with version
4, but flexfiles takes its version tuple from GETDEVICEINFO per device,
and one address can legitimately serve both NFSv3 and NFSv4.

Two deviceids on one address with different ds_versions[0].version
therefore share a single nfs4_pnfs_ds, and whichever mirror connects
first pins ds_clp to its own version. The other one is handed that
client anyway, so it selects rpc_call_ops for a version the connection
does not speak, and the mismatched sequence-slot handling dereferences
NULL.

Add the version to the cache key so the two cannot alias, giving each
version its own nfs4_pnfs_ds and connection while both mirrors stay
usable. Only the major version is compared, since that is what selects
rpc_call_ops and rpc_ops; v4.0 and v4.1 keep sharing a client. The files
layout driver passes the 4 it already hardcodes at connect time.

## Which versions are affected by CVE-2026-90102?


## How do I fix CVE-2026-90102?

Apply the vendor's patch.

## Is CVE-2026-90102 being exploited?

There is no known exploitation of CVE-2026-90102 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90102 and fix it if it is affected.

What it is: CVE-2026-90102 is a high-severity vulnerability in Linux, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-90102 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-2026-90102/ (Markdown: https://insights.sbomify.com/CVE-2026-90102/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90102
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90102
- OSV: https://osv.dev/vulnerability/CVE-2026-90102

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90102/
Summaries are generated and may contain mistakes; the official description above is the record.