CVE-2026-23039

A NULL pointer dereference vulnerability was found in the Linux kernel's GUD (Generic USB Display) driver. When a USB display is disconnected, drm_atomic_helper_disable_all() sets the framebuffer and CRTC pointers to NULL before invoking a commit. The driver then attempts to dereference these NULL pointers, causing a kernel crash on every USB display disconnect event.

This vulnerability affects systems using USB displays with the GUD driver. Every disconnect of a GUD-compatible USB display causes a kernel crash, making the driver effectively unusable for hot-plug scenarios. Physical access to connect/disconnect USB displays is required to trigger the crash.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, prevent the gud module from being loaded if USB displays are not required. See https://access.redhat.com/solutions/41278 for instructions on how to blacklist a kernel module.