# CVE-2026-89701: nfsd: validate nseconds in TIME_DELEG decode paths

> A missing validation in the Linux kernel NFS server allows remote attackers to cause a denial of service via malformed time values.

- **Severity:** Not scored
- **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-2026-89701, DEBIAN-CVE-2026-89701, GHSA-pqvp-pfwp-hf4c, UBUNTU-CVE-2026-89701

## What is CVE-2026-89701?

CVE-2026-89701 is a denial of service 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: validate nseconds in TIME_DELEG decode paths

The xdrgen-based TIME_DELEG_ACCESS and TIME_DELEG_MODIFY decode arms
store a raw uint32_t nseconds directly into tv_nsec without enforcing
nseconds < NSEC_PER_SEC. The legacy nfsd4_decode_nfstime4 has this
check but the TIME_DELEG paths do not. A malformed timespec can
propagate through notify_change() to disk.

Add range checks in both nfs4xdr.c (SETATTR path) and
nfs4callback.c (CB_GETATTR path).

## Which versions are affected by CVE-2026-89701?


## How do I fix CVE-2026-89701?

Apply the vendor's patch.

## Is CVE-2026-89701 being exploited?

There is no known exploitation of CVE-2026-89701 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89701 and fix it if it is affected.

What it is: CVE-2026-89701 is a denial of service 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-2026-89701 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-2026-89701/ (Markdown: https://insights.sbomify.com/CVE-2026-89701/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89701
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89701
- OSV: https://osv.dev/vulnerability/CVE-2026-89701

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89701/
Summaries are generated and may contain mistakes; the official description above is the record.