# CVE-2026-89669: nfsd: initialize copy-notify stateid before publishing it

> A race condition in the Linux kernel NFS server allows attackers to trigger a use-after-free via crafted OFFLOAD_CANCEL requests, potentially leading to code execution or crashes.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100076, BELL-CVE-2026-89669, DEBIAN-CVE-2026-89669, GHSA-76rg-3h22-jw6r, UBUNTU-CVE-2026-89669

## What is CVE-2026-89669?

CVE-2026-89669 is a critical use after free vulnerability in Linux, published on 11 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:

nfsd: initialize copy-notify stateid before publishing it

nfsd4_copy_notify() finished initializing the cpntf state after
nfs4_alloc_init_cpntf_state() had already linked it into the
s2s_cp_stateids IDR and the parent's sc_cp_list, with cs_count == 1 (the
membership reference) and none held for the caller. A racing
OFFLOAD_CANCEL (crafted cl_id == nn->s2s_cp_cl_id plus the guessable
so_id) could reach manage_cpntf_state() and free the entry, turning the
caller's subsequent cpn_cnr_stateid read and cp_p_stateid/cp_p_clid
writes into use-after-free. The owning clientid was also only recorded
after publication, so it could not gate an ownership check in that window.

Record cp_p_stateid and cp_p_clid inside nfs4_alloc_init_cpntf_state()
before nfs4_init_cp_state() publishes the entry, and return it with an
extra reference. The caller reads the stateid under that reference and
drops it with nfs4_put_cpntf_state(); on a late error the laundromat
reaps the entry.

## Which versions are affected by CVE-2026-89669?


## How do I fix CVE-2026-89669?

Apply the vendor's patch.

## Is CVE-2026-89669 being exploited?

There is no known exploitation of CVE-2026-89669 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89669 and fix it if it is affected.

What it is: CVE-2026-89669 is a critical use after free vulnerability in Linux, published on 11 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-2026-89669 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-2026-89669/ (Markdown: https://insights.sbomify.com/CVE-2026-89669/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89669
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89669
- OSV: https://osv.dev/vulnerability/CVE-2026-89669

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89669/
Summaries are generated and may contain mistakes; the official description above is the record.