CVE-2025-40275 ALSA: usb-audio: Fix NULL pointer dereference in snd_usb_mixer_controls_badd
A local attacker with physical access can cause a kernel crash by connecting a malicious USB audio device due to a missing NULL check.
- 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-2025-40275?
CVE-2025-40275 is a vulnerability in Linux, published on 6 Dec 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 dereference in snd_usb_mixer_controls_badd
In snd_usb_create_streams(), for UAC version 3 devices, the Interface Association Descriptor (IAD) is retrieved via usb_ifnum_to_if(). If this call fails, a fallback routine attempts to obtain the IAD from the next interface and sets a BADD profile. However, snd_usb_mixer_controls_badd() assumes that the IAD retrieved from usb_ifnum_to_if() is always valid, without performing a NULL check. This can lead to a NULL pointer dereference when usb_ifnum_to_if() fails to find the interface descriptor.
This patch adds a NULL pointer check after calling usb_ifnum_to_if() in snd_usb_mixer_controls_badd() to prevent the dereference.
This issue was discovered by syzkaller, which triggered the bug by sending a crafted USB device descriptor.
Which versions are affected by CVE-2025-40275?
How do I fix CVE-2025-40275?
Apply the vendor's patch.
Is CVE-2025-40275 being exploited?
There is no known exploitation of CVE-2025-40275 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40275, DEBIAN-CVE-2025-40275, GHSA-x49w-vx84-7x88, ROOT-OS-DEBIAN-12-CVE-2025-40275, ROOT-OS-DEBIAN-13-CVE-2025-40275, ROOT-OS-UBUNTU-2204-CVE-2025-40275 and 2 more.