CVE-2025-21776 USB: hub: Ignore non-compliant devices with too many configs or interfaces
A malicious USB device with excessive configurations can cause a kernel crash via null pointer dereference in the USB hub driver.
- 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
What is CVE-2025-21776?
CVE-2025-21776 is a medium-severity vulnerability in Linux kernel, published on 27 Feb 2025. 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: hub: Ignore non-compliant devices with too many configs or interfaces
Robert Morris created a test program which can cause usb_hub_to_struct_hub() to dereference a NULL or inappropriate pointer:
Oops: general protection fault, probably for non-canonical address 0xcccccccccccccccc: 0000 [#1] SMP DEBUG_PAGEALLOC PTI CPU: 7 UID: 0 PID: 117 Comm: kworker/7:1 Not tainted 6.13.0-rc3-00017-gf44d154d6e3d #14 Hardware name: FreeBSD BHYVE/BHYVE, BIOS 14.0 10/17/2021 Workqueue: usb_hub_wq hub_event RIP: 0010:usb_hub_adjust_deviceremovable+0x78/0x110 ... Call Trace: <TASK> ? die_addr+0x31/0x80 ? exc_general_protection+0x1b4/0x3c0 ? asm_exc_general_protection+0x26/0x30 ? usb_hub_adjust_deviceremovable+0x78/0x110 hub_probe+0x7c7/0xab0 usb_probe_interface+0x14b/0x350 really_probe+0xd0/0x2d0 ? __pfx___device_attach_driver+0x10/0x10 __driver_probe_device+0x6e/0x110 driver_probe_device+0x1a/0x90 __device_attach_driver+0x7e/0xc0 bus_for_each_drv+0x7f/0xd0 __device_attach+0xaa/0x1a0 bus_probe_device+0x8b/0xa0 device_add+0x62e/0x810 usb_set_configuration+0x65d/0x990 usb_generic_driver_probe+0x4b/0x70 usb_probe_device+0x36/0xd0
The cause of this error is that the device has two interfaces, and the hub driver binds to interface 1 instead of interface 0, which is where usb_hub_to_struct_hub() looks.
We can prevent the problem from occurring by refusing to accept hub devices that violate the USB spec by having more than one configuration or interface.
Weakness: CWE-476
Which versions are affected by CVE-2025-21776?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-21776?
Apply the vendor's patch.
Is CVE-2025-21776 being exploited?
There is no known exploitation of CVE-2025-21776 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-57813, AZL-57890, BELL-CVE-2025-21776, DEBIAN-CVE-2025-21776, GHSA-4r7g-qqxf-m6v8, ROOT-OS-UBUNTU-2404-CVE-2025-21776 and 1 more.