# CVE-2026-89481: nvme-tcp: fix host memory disclosure on R2T for a read command

> A malicious NVMe controller can trigger host memory disclosure by sending an R2T for a read command, leaking stale kernel data.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **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-100646, BELL-CVE-2026-89481, DEBIAN-CVE-2026-89481, GHSA-fmg2-x8fr-fw62, UBUNTU-CVE-2026-89481

## What is CVE-2026-89481?

CVE-2026-89481 is a high-severity 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:

nvme-tcp: fix host memory disclosure on R2T for a read command

nvme_tcp_handle_r2t() does not check the direction of the request the
R2T refers to. A malicious controller can send an R2T for a READ and
the host will answer it: nvme_tcp_setup_h2c_data_pdu() builds the
H2CData header and nvme_tcp_try_send_data() sends the request's data
buffer. That buffer is the READ destination, so its contents go to the
controller.

The command then completes normally and nothing is logged.

Against a test controller that answers every READ with an R2T, a 4096
byte buffered read returned all 4096 bytes, split over two R2Ts. The
pages contained stale kernel data, including an array of struct page
pointers.

Reject an R2T for a request that is not a write.

## Which versions are affected by CVE-2026-89481?


## How do I fix CVE-2026-89481?

Apply the vendor's patch.

## Is CVE-2026-89481 being exploited?

There is no known exploitation of CVE-2026-89481 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89481 and fix it if it is affected.

What it is: CVE-2026-89481 is a high-severity 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-2026-89481 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-2026-89481/ (Markdown: https://insights.sbomify.com/CVE-2026-89481/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89481
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89481
- OSV: https://osv.dev/vulnerability/CVE-2026-89481

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89481/
Summaries are generated and may contain mistakes; the official description above is the record.