# CVE-2026-89652: ceph: bound copied dentry name length in NFS export get_name

> A malicious Ceph MDS can trigger a buffer overflow in the Linux kernel NFS export path, potentially allowing code execution or denial of service.

- **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-100566, BELL-CVE-2026-89652, DEBIAN-CVE-2026-89652, GHSA-rgf4-v7fw-49xj, UBUNTU-CVE-2026-89652

## What is CVE-2026-89652?

CVE-2026-89652 is a critical memory corruption 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:

ceph: bound copied dentry name length in NFS export get_name

ceph_get_name() copies the MDS-supplied name into the caller's
NAME_MAX-sized buffer with memcpy(name, rinfo->dname, rinfo->dname_len)
and then writes name[rinfo->dname_len] = 0, without checking dname_len
against NAME_MAX. A malicious or buggy MDS that returns a LOOKUPNAME reply
with dname_len > NAME_MAX overflows the buffer. __get_snap_name() copies
rde->name / rde->name_len the same unchecked way.

Impact: a malicious or compromised Ceph MDS overflows the NAME_MAX name
buffer in a client's NFS-export get_name path, a slab out-of-bounds write
reported by KASAN. Reachable when a CephFS mount is re-exported over NFS.

Add ceph_export_copy_name(), which rejects lengths above NAME_MAX with
-ENAMETOOLONG before the copy, and use it in both ceph_get_name() and
__get_snap_name().

## Which versions are affected by CVE-2026-89652?


## How do I fix CVE-2026-89652?

Apply the vendor's patch.

## Is CVE-2026-89652 being exploited?

There is no known exploitation of CVE-2026-89652 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89652 and fix it if it is affected.

What it is: CVE-2026-89652 is a critical memory corruption 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-2026-89652 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-2026-89652/ (Markdown: https://insights.sbomify.com/CVE-2026-89652/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89652
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89652
- OSV: https://osv.dev/vulnerability/CVE-2026-89652

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89652/
Summaries are generated and may contain mistakes; the official description above is the record.