CVE-2026-74678

The AX88179_178A USB Ethernet driver in the Linux kernel leaks kernel memory when the scatter‑gather flag (NETIF_F_SG) is enabled and a packet buffer cannot be linearized. In this scenario, the driver’s transmit helper returns NULL without freeing the original socket buffer, and the higher‑level function treats this as a packet drop without deallocating the leaked skb. Each failed linearization under memory pressure creates a memory leak that accumulates with every transmitted frame, potentially exhausting kernel memory and destabilizing or crashing the system.

All Linux systems that compile the kernel with the built‑in ax88179_178a driver and expose a USB network interface using that chipset are affected. No specific release numbers are identified, so any kernel build that contains this driver before the commit that fixes the leak is vulnerable.

The CVSS score of 7.5 indicates that the vulnerability is high severity, while the EPSS score of < 1% suggests a very low but nonzero probability of exploitation, and it is not listed in CISA KEV. The likely attack vector is through sending network traffic over the affected USB NIC when scatter‑gather is enabled; thus any process capable of transmitting packets—whether local or remote—can trigger the memory leak. The result is a denial‑of‑service condition via kernel resource exhaustion rather than privilege escalation or remote code execution.