Linux Kernel ksmbd CVE-2026-31409

Upgrade to patched Linux kernel versions: 6.1.167 or later for the 6.1.x LTS series, 6.6.130 or later for 6.6.x LTS, 6.12.78 or later for 6.12.x stable, 6.18.20 or later for 6.18.x, 6.19.10 or later for 6.19.x, or 7.0-rc5 or later for mainline. Patches available from kernel.org stable tree at the URLs listed in references. For systems unable to immediately patch, disable ksmbd multichannel support by setting 'multichannel = no' in ksmbd configuration (/etc/ksmbd/smb.conf or equivalent), though this eliminates performance benefits and may break clients requiring multichannel. Alternatively, disable ksmbd entirely (rmmod ksmbd) and use Samba instead if SMB server functionality is required, though this requires significant reconfiguration and may impact performance in embedded environments where ksmbd is preferred for lower resource usage. If ksmbd must remain enabled with multichannel, restrict SMB access to trusted networks only via firewall rules (block TCP 445/139 from untrusted sources) to limit attacker authentication opportunities, though this does not eliminate risk from insider threats or compromised credentials. Monitor ksmbd logs for repeated binding failures which may indicate exploitation attempts. Note that disabling multichannel may cause connection issues for Windows 10/11 clients configured to require it.