Bug 2516262 (CVE-2026-72483)

Summary: CVE-2026-72483 kernel: usb: host: max3421: Fix shift-out-of-bounds in max3421_hub_control()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's USB host driver, specifically in the `max3421_hub_control()` function. A malicious userspace task with access to the root hub can trigger a shift-out-of-bounds vulnerability by issuing a crafted `USBDEVFS_CONTROL` ioctl. This can lead to arbitrary bit corruption of the `port_status`, potentially bypassing internal state checks and confusing the hub's operational status.
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Description OSIDB Bzimport 2026-08-15 06:03:16 UTC 
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.
Comment 1 gkamathe 2026-08-17 14:46:32 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081537-CVE-2026-72483-3aa6@gregkh/T