# CVE-2026-89728: i3c: renesas: Fix out-of-bounds access for newdevs mask

> An out-of-bounds access in the Renesas I3C driver can cause a crash or memory corruption when the I3C bus is empty during Dynamic Address Assignment.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **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:** DEBIAN-CVE-2026-89728, GHSA-hwqr-35ww-7c42, UBUNTU-CVE-2026-89728

## What is CVE-2026-89728?

CVE-2026-89728 is a memory corruption 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:

i3c: renesas: Fix out-of-bounds access for newdevs mask

When software initiates DAA (Dynamic Address Assignment), the controller
reports the result via the NRSPQP (Normal Response Queue Port Register).
The data length field of the response descriptor, which is accessible
through the NRSPQP register, indicates the number of devices remaining
after DAA. Consequently, when the bus is empty, this field contains the
maximum number of devices supported by the controller (8 for the Renesas
I3C controller).

Adjust the condition that computes the newly discovered devices bitmask
to prevent an out-of-bounds when the I3C bus is empty.

## Which versions are affected by CVE-2026-89728?


## How do I fix CVE-2026-89728?

Apply the vendor's patch.

## Is CVE-2026-89728 being exploited?

There is no known exploitation of CVE-2026-89728 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89728 and fix it if it is affected.

What it is: CVE-2026-89728 is a memory corruption 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-2026-89728 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-2026-89728/ (Markdown: https://insights.sbomify.com/CVE-2026-89728/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89728
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89728
- OSV: https://osv.dev/vulnerability/CVE-2026-89728

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89728/
Summaries are generated and may contain mistakes; the official description above is the record.