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.
CVSS Details
- CVSS 3.1 Base Score: 7.8
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Debian | — | Upgrade linux | Aug 16, 2026 | Aug 16, 2026 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Aug 21, 2026 | Aug 15, 2026 |
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