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

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Published: 2026-08-15 · Updated: 2026-08-17

## Affected

- Linux: version range not reported
- Linux: 3.16

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
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## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/e5fa9d8f40746ec3447335c9642c03410f5fd3af
- https://git.kernel.org/stable/c/08b1d4cab0230697bc74c63fc4e40170a7559c54
- https://git.kernel.org/stable/c/3be5f24e8270ba53b3c814d13689bb8644c86237
- https://git.kernel.org/stable/c/d512bdefd241b98f4d7bcb5bab5614a86411fad4
- https://git.kernel.org/stable/c/00dd025324b56d39d37e57a08f473dab3a660f30
- https://git.kernel.org/stable/c/02d03c61e8a7b016956acb48e8a2512d16d87517
- https://git.kernel.org/stable/c/4da073d57176d8e1c2bca34febfbc81d2560c1a5
- https://git.kernel.org/stable/c/cff06b03b530ae1fe8a13e93a7848f2130e00fb4

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