# CVE-2026-89703: nfsd: set SC_STATUS_FREED in nfsd4_drop_revoked_stid for delegations

> A use-after-free in the Linux kernel NFS server allows attackers to cause denial of service or execute arbitrary code via revoked delegations.

- **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:** BELL-CVE-2026-89703, DEBIAN-CVE-2026-89703, GHSA-4288-gh8m-45g7, UBUNTU-CVE-2026-89703

## What is CVE-2026-89703?

CVE-2026-89703 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: set SC_STATUS_FREED in nfsd4_drop_revoked_stid for delegations

nfsd4_drop_revoked_stid() handles FREE_STATEID for admin-revoked
delegations but does not set SC_STATUS_FREED before releasing cl_lock.
revoke_delegation() uses this flag to detect whether FREE_STATEID has
already processed the delegation -- without it, the freed delegation is
added to cl_revoked via list_add(), producing a use-after-free when
cl_revoked is later traversed in __destroy_client().

The SC_STATUS_REVOKED path in nfsd4_free_stateid() (line 7983) already
sets SC_STATUS_FREED correctly. Apply the same pattern to the
SC_STATUS_ADMIN_REVOKED path in nfsd4_drop_revoked_stid().

## Which versions are affected by CVE-2026-89703?


## How do I fix CVE-2026-89703?

Apply the vendor's patch.

## Is CVE-2026-89703 being exploited?

There is no known exploitation of CVE-2026-89703 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89703 and fix it if it is affected.

What it is: CVE-2026-89703 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-2026-89703 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-2026-89703/ (Markdown: https://insights.sbomify.com/CVE-2026-89703/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89703
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89703
- OSV: https://osv.dev/vulnerability/CVE-2026-89703

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89703/
Summaries are generated and may contain mistakes; the official description above is the record.