CVE-2026-90023 usb: gadget: f_mass_storage: fix null pointer dereference in fsg_common_set_num_buffers()

Q: Is CVE-2026-90023 being exploited?

There is no known exploitation of CVE-2026-90023 in the wild and no public exploit code.

Not scored Published 16 Sep 2026 Updated 21 Oct 2026

A local attacker with access to USB gadget configuration can trigger a null pointer dereference in the Linux kernel, causing a system crash.

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-2026-90023?

CVE-2026-90023 is a vulnerability in Linux, published on 16 Sep 2026. 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_mass_storage: fix null pointer dereference in fsg_common_set_num_buffers()

Previously fsg_num_buffers_validate() was removed as it was not necessary due to Kconfig setting the limits for n from 2 to 256 with default as 2. However, setting the page content in such a way that kstrtou8() reflects n value as either 0 or 1 bypasses these restrictions leading to a null pointer dereference if n is 0. Fix this by adding a check for n < 2 and returning -EINVAL if n is either 0 or 1 consistent with Kconfig logic.

Which versions are affected by CVE-2026-90023?

How do I fix CVE-2026-90023?

Apply the vendor's patch.

Is CVE-2026-90023 being exploited?