CVE-2025-40085 ALSA: usb-audio: Fix NULL pointer deference in try_to_register_card
A local attacker with physical access can cause a kernel crash by connecting a malicious USB audio device, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2025-40085?
CVE-2025-40085 is a vulnerability in Linux, published on 29 Oct 2025. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usb-audio: Fix NULL pointer deference in try_to_register_card
In try_to_register_card(), the return value of usb_ifnum_to_if() is passed directly to usb_interface_claimed() without a NULL check, which will lead to a NULL pointer dereference when creating an invalid USB audio device. Fix this by adding a check to ensure the interface pointer is valid before passing it to usb_interface_claimed().
Which versions are affected by CVE-2025-40085?
How do I fix CVE-2025-40085?
Apply the vendor's patch.
Is CVE-2025-40085 being exploited?
There is no known exploitation of CVE-2025-40085 in the wild and no public exploit code.
Sources
Also known as AZL-69030, BELL-CVE-2025-40085, DEBIAN-CVE-2025-40085, GHSA-2cjq-ppmx-48x5, ROOT-OS-DEBIAN-12-CVE-2025-40085, ROOT-OS-DEBIAN-13-CVE-2025-40085 and 3 more.