CVE-2025-40092

A low severity NULL pointer dereference flaw was found in the Linux kernel's USB gadget Network Control Model (NCM) function driver (f_ncm). After a bind/unbind cycle, the ncm->notify_req pointer is left stale; if a subsequent bind of the function fails, the unified error-handling path attempts to free this stale request, causing a NULL pointer dereference when accessing ep->ops->free_request in usb_ep_free_request(), which results in a kernel crash (denial of service). Red Hat Product Security rated this flaw LOW severity with a CVSS3 base score of 5.5 (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H), because exploitation requires local privileged access to trigger the affected error path and the impact is limited to system availability. This differs from the upstream CVEORG score of 7.8, which assigns high confidentiality and integrity impacts; the technical evidence supports only a denial of service from the NULL pointer dereference, with no confidentiality or integrity impact. Red Hat Enterprise Linux 6, 7, 8, and 9 (kernel and kernel-rt) are not affected because the vulnerable code is not present in those streams. The Red Hat Enterprise Linux 10 kernel and the Red Hat In-Vehicle OS 1 kernel are affected; the fix is deferred to a future update because this is a low-severity flaw in a configuration-dependent error handling path, and the residual risk is limited to a kernel panic (denial of service) on systems using the USB NCM gadget function.