# CVE-2026-89699: nfsd: validate symlink target length in NFSv4 CREATE

> A remote attacker can cause memory exhaustion in the Linux kernel NFS server by sending oversized symlink targets, leading to denial of service.

- **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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100310, BELL-CVE-2026-89699, DEBIAN-CVE-2026-89699, GHSA-864v-pq9r-vg9w, UBUNTU-CVE-2026-89699

## What is CVE-2026-89699?

CVE-2026-89699 is a high-severity 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 symlink target length in NFSv4 CREATE

nfsd4_decode_create() accepts an unbounded cr_datalen from the wire for
NF4LNK symlink targets, allowing a client to force a kmalloc of up to
the maximum RPC payload size (several MiB) per COMPOUND op that persists
until compound teardown.  The VFS rejects oversized targets with
ENAMETOOLONG, but the allocation has already occurred.

Reject cr_datalen == 0 early with nfserr_inval and cr_datalen greater
than NFS4_MAXPATHLEN (PATH_MAX) with nfserr_nametoolong to bound the
allocation.

## Which versions are affected by CVE-2026-89699?


## How do I fix CVE-2026-89699?

Apply the vendor's patch.

## Is CVE-2026-89699 being exploited?

There is no known exploitation of CVE-2026-89699 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89699 and fix it if it is affected.

What it is: CVE-2026-89699 is a high-severity 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-2026-89699 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-2026-89699/ (Markdown: https://insights.sbomify.com/CVE-2026-89699/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89699
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89699
- OSV: https://osv.dev/vulnerability/CVE-2026-89699

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89699/
Summaries are generated and may contain mistakes; the official description above is the record.