CVE-2025-68289: 
Linux Kernel vulnerability analysis and mitigation

CVE-2025-68289 is a memory leak vulnerability in the Linux kernel's USB gadget Ethernet Emulation Model (EEM) function (f_eem). The flaw exists in the eem_unwrap function, which failed to properly free allocated resources when usb_ep_queue operations fail in the command path. It was published on December 16, 2025, and affects multiple Linux kernel stable branches prior to patched versions including 5.10.247, 5.15.197, 6.1.159, 6.6.119, 6.12.61, 6.17.11, and 6.18. The CVSS v3.1 base score is 5.5 (Medium) (Red Hat CVE, Feedly).

The root cause is improper resource management (CWE-401: Missing Release of Memory after Effective Lifetime) in the eem_unwrap function within drivers/usb/gadget/function/f_eem.c. When usb_ep_queue fails in the command processing path, the code did not release previously allocated objects including cloned socket buffers (skb_clone), USB endpoint requests (usb_ep_alloc_request), and kmalloc-allocated buffers. The attack vector is local (requiring low-privileged access), and exploitation involves triggering repeated usb_ep_queue failures — for example, by interacting with a USB gadget EEM interface under error conditions. kmemleak analysis confirmed multiple unreferenced memory objects (sizes 240, 256, 128, and 64 bytes) accumulating in the eem_unwrap call path (Feedly).

Successful exploitation causes progressive memory exhaustion on the affected system, leading to performance degradation, reduced system stability, and potentially system crashes or unresponsiveness over time. The vulnerability has no confidentiality or integrity impact; the sole consequence is availability loss (CVSS A:H). Systems acting as USB gadget EEM devices in USB-intensive environments are most at risk (Feedly, Red Hat CVE).

Apply the upstream kernel patches that fix the eem_unwrap error handling. Fixed versions include Linux kernel 5.10.247, 5.15.197, 6.1.159, 6.6.119, 6.12.61, 6.17.11, and 6.18 and later. Downstream distributions including Debian (DLA-4436-1), Ubuntu (USN-8094-x, USN-8096-x, USN-8116-1, USN-8152-1), and Oracle Linux have released updated kernel packages. As an interim measure, monitor system memory usage closely on systems using USB gadget EEM functionality, and consider disabling the EEM gadget function if not required (Red Hat CVE, Debian LTS, Ubuntu USN-8094-1).