# CVE-2026-89559: libnvdimm/labels: Prevent integer overflow in __nd_label_validate()

> An integer overflow in the Linux kernel's libnvdimm module allows an out-of-bounds write, potentially leading to code execution or denial of service.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100244, BELL-CVE-2026-89559, DEBIAN-CVE-2026-89559, GHSA-cp82-3r67-94rf, UBUNTU-CVE-2026-89559

## What is CVE-2026-89559?

CVE-2026-89559 is a high-severity vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

libnvdimm/labels: Prevent integer overflow in __nd_label_validate()

The on-media namespace index field nslot is a u32 read from the DIMM
label storage area.  __nd_label_validate() bounds it against the config
area size, but sizeof_namespace_label() returns unsigned, so the product
nslot * label_size is evaluated in 32-bit and wraps modulo 2^32 before
the comparison.  A crafted nslot passes the bound and is then used as the
loop trip count in nd_label_data_init(), whose memset() walks off the end
of the config_size buffer: an out-of-bounds write.

The field is not trusted -- it comes from the medium, or from userspace
via ND_CMD_SET_CONFIG_DATA.  Evaluate the product in 64-bit so the bound
check is exact; conforming labels are unaffected.

The check was safe when introduced by commit 4a826c83db4e ("libnvdimm:
namespace indices: read and validate"): it multiplied by sizeof(struct
nd_namespace_label), a size_t, so on a 64-bit build the product did not
wrap.  Commit 564e871aa66f ("libnvdimm, label: add v1.2 nvdimm label
definitions") narrowed it to 32 bits when the label size became a runtime
value read via sizeof_namespace_label().

## Which versions are affected by CVE-2026-89559?


## How do I fix CVE-2026-89559?

Apply the vendor's patch.

## Is CVE-2026-89559 being exploited?

There is no known exploitation of CVE-2026-89559 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89559 and fix it if it is affected.

What it is: CVE-2026-89559 is a high-severity vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-89559 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-2026-89559/ (Markdown: https://insights.sbomify.com/CVE-2026-89559/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89559
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89559
- OSV: https://osv.dev/vulnerability/CVE-2026-89559

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89559/
Summaries are generated and may contain mistakes; the official description above is the record.