# CVE-2026-72483: usb: host: max3421: Fix shift-out-of-bounds in max3421_hub_control()

> A local attacker can trigger undefined behavior in the max3421 USB driver via a crafted ioctl, potentially corrupting state and causing denial of service or privilege escalation.

- **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:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-72483, DEBIAN-CVE-2026-72483, GHSA-fc4h-xff9-jp24, UBUNTU-CVE-2026-72483

## What is CVE-2026-72483?

CVE-2026-72483 is a high-severity vulnerability in Linux, published on 15 Aug 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: host: max3421: Fix shift-out-of-bounds in max3421_hub_control()

The `max3421_hub_control()` function handles USB hub class requests
to the virtual root hub. In the `default` branches of both the
`ClearPortFeature` and `SetPortFeature` switch statements, it modifies
`max3421_hcd->port_status` by left shifting 1 by the request's `value`
parameter. However, it does not validate whether this shift will exceed
the width of `port_status`.

So if a malicious userspace task with access to the root hub via
/dev/bus/usb/.../001 issues a USBDEVFS_CONTROL ioctl with `wValue`
greater than or equal to 32, the left shift operation invokes
shift-out-of-bounds undefined behavior. This results in arbitrary
bit corruption of `port_status`, including the normally-immutable
change bits, which can bypass internal state checks and confuse the
hub status.

Fix this by rejecting requests whose `value` exceeds the shift width
before performing the shift.

This issue was found using a KLEE-based symbolic execution tool for
kernel drivers that I'm currently developing.

## Which versions are affected by CVE-2026-72483?


## How do I fix CVE-2026-72483?

Apply the vendor's patch.

## Is CVE-2026-72483 being exploited?

There is no known exploitation of CVE-2026-72483 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72483 and fix it if it is affected.

What it is: CVE-2026-72483 is a high-severity vulnerability in Linux, published on 15 Aug 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-2026-72483 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-2026-72483/ (Markdown: https://insights.sbomify.com/CVE-2026-72483/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72483
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72483
- OSV: https://osv.dev/vulnerability/CVE-2026-72483

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72483/
Summaries are generated and may contain mistakes; the official description above is the record.