The Linux kernel eMS USB driver suffers a memory leak in the URB completion callback. When an inbound USB transfer completes, the URB is unanchored by the USB subsystem before the driver’s callback is invoked, so the URB is never freed unless the device is closed. The unreleased memory accumulates with each transfer, allowing a sustained leak that can exhaust kernel memory and degrade system responsiveness. The flaw maps to CWE‑401, a missing release of memory after its effective lifetime.

Any system running a Linux kernel that includes the eMS USB driver is potentially affected, regardless of distribution. The advisory does not specify a version range; only kernels that contain the unpatched code before the reference commit are at risk. Updated kernels that contain the fix commit are not vulnerable.

The CVSS score of 7.0 marks this issue as high severity. The EPSS score of less than 1% indicates that, at present, exploitation is unlikely outside of a targeted attack. Based on the description, the likely attack vector is local or physical access to the affected machine to attach a malicious or traffic‑heavy USB device that repeatedly triggers the callback. The vulnerability does not appear in the CISA KEV list. A successful exploitation could force the system into a memory‑starved state, effectively denying service.