CVE-2026-64327

A flaw was found in the Linux kernel's FunctionFS (f_fs) module, which handles USB gadget functionality. This vulnerability occurs because the endpoint direction (epfile->in) was not correctly initialized until a USB host connected. Consequently, early operations initiated by userspace programs could encounter incorrect data transfer directions, potentially leading to unintended data access or corruption.

This vulnerability is assessed as a Moderate severity issue because exploitation requires local userspace privileges to interact with USB gadget endpoints prior to host connection, confining the blast radius to local memory corruption or denial of service rather than remote compromise. Standard Red Hat Enterprise Linux deployments do not configure or expose USB gadget FunctionFS interfaces by default, as they necessitate specialized peripheral hardware controllers. Furthermore, the vulnerable endpoint initialization logic is not present in supported Red Hat Enterprise Linux kernels.

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.