CVE-2026-31609

A flaw was found in the Linux kernel's Server Message Block (SMB) client. This vulnerability, a double-free, occurs in the smbd_free_send_io() function after smbd_send_batch_flush() has already freed the memory. This memory corruption can lead to a denial of service (DoS) for the affected system.

SMB Direct batch flush could double-free send I/O structures; upstream orders frees correctly. Red Hat recommends patched kernels for SMB client users leveraging RDMA/Direct. Unload cifs where SMB client access is not needed.

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.

To mitigate this issue, prevent the cifs module from being loaded. See https://access.redhat.com/solutions/41278 for instructions.