# CVE-2026-63904: usb: usbtmc: check URB actual_length for interrupt-IN notifications

> A malicious USB device can trigger an out-of-bounds read in the Linux kernel USBTMC driver, potentially leaking memory or causing a crash.

- **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:** 19 Jul 2026
- **Updated:** 19 Jul 2026
- **Also known as:** BELL-CVE-2026-63904, DEBIAN-CVE-2026-63904, GHSA-7gx5-8c2m-vqr5, ROOT-OS-UBUNTU-2204-CVE-2026-63904, UBUNTU-CVE-2026-63904

## What is CVE-2026-63904?

CVE-2026-63904 is a memory corruption vulnerability in Linux, published on 19 Jul 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:

usb: usbtmc: check URB actual_length for interrupt-IN notifications

USBTMC devices can use an optional interrupt endpoint for notification
messages. These typically contain two-byte headers indicating the
payload format, but the driver does not check if these headers are
present before accessing the data buffers. In cases where the URB
actual_length is not enough to fit these headers, the driver will either
cause an out-of-bounds read, or consume stale leftover data from a
previous notification.

Fix by checking if actual_data contains enough bytes for the headers,
otherwise resubmit URB to the interrupt endpoint.

## Which versions are affected by CVE-2026-63904?


## How do I fix CVE-2026-63904?

Apply the vendor's patch.

## Is CVE-2026-63904 being exploited?

There is no known exploitation of CVE-2026-63904 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63904 and fix it if it is affected.

What it is: CVE-2026-63904 is a memory corruption vulnerability in Linux, published on 19 Jul 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-2026-63904 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-2026-63904/ (Markdown: https://insights.sbomify.com/CVE-2026-63904/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63904
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63904
- OSV: https://osv.dev/vulnerability/CVE-2026-63904

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63904/
Summaries are generated and may contain mistakes; the official description above is the record.