CVE-2025-40094 usb: gadget: f_acm: Refactor bind path to use __free()
A NULL pointer dereference in the Linux kernel USB ACM gadget driver allows local attackers to cause a system crash via a failed bind operation.
- 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-2025-40094?
CVE-2025-40094 is a high-severity vulnerability in Linux, published on 30 Oct 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: gadget: f_acm: Refactor bind path to use __free()
After an bind/unbind cycle, the acm->notify_req is left stale. If a subsequent bind fails, the unified error label attempts to free this stale request, leading to a NULL pointer dereference when accessing ep->ops->free_request.
Refactor the error handling in the bind path to use the __free() automatic cleanup mechanism.
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020 Call trace: usb_ep_free_request+0x2c/0xec gs_free_req+0x30/0x44 acm_bind+0x1b8/0x1f4 usb_add_function+0xcc/0x1f0 configfs_composite_bind+0x468/0x588 gadget_bind_driver+0x104/0x270 really_probe+0x190/0x374 __driver_probe_device+0xa0/0x12c driver_probe_device+0x3c/0x218 __device_attach_driver+0x14c/0x188 bus_for_each_drv+0x10c/0x168 __device_attach+0xfc/0x198 device_initial_probe+0x14/0x24 bus_probe_device+0x94/0x11c device_add+0x268/0x48c usb_add_gadget+0x198/0x28c dwc3_gadget_init+0x700/0x858 __dwc3_set_mode+0x3cc/0x664 process_scheduled_works+0x1d8/0x488 worker_thread+0x244/0x334 kthread+0x114/0x1bc ret_from_fork+0x10/0x20
Which versions are affected by CVE-2025-40094?
How do I fix CVE-2025-40094?
Apply the vendor's patch.
Is CVE-2025-40094 being exploited?
There is no known exploitation of CVE-2025-40094 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40094, DEBIAN-CVE-2025-40094, GHSA-qr6v-84mv-g36r, ROOT-OS-DEBIAN-11-CVE-2025-40094, ROOT-OS-DEBIAN-12-CVE-2025-40094, ROOT-OS-DEBIAN-13-CVE-2025-40094 and 3 more.