CVE-2026-31717: Linux Kernel

High severity, CVSS 8.8. EPSS: 0.6% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate owner of durable handle on reconnect Currently, ksmbd does not verify if the user attempting to reconnect to a durable handle is the same user who originally opened the file. This allows any authenticated user to hijack an orphaned durable handle by predicting or brute-forcing the persistent ID. According to MS-SMB2, the server MUST verify that the SecurityContext of the reconnect request matches the SecurityContext associated with the existing open. Add a durable_owner structure to ksmbd_file to store the original opener's UID, GID, and account name. and catpure the owner information when a file handle becomes orphaned. and implementing ksmbd_vfs_compare_durable_owner() to validate the identity of the requester during SMB2_CREATE (DHnC).

Affected products

• Linux Linux Kernel: from 6.6.32, before 6.7 (fixed in 6.7); from 6.9, before 6.18.25 (fixed in 6.18.25); from 6.19, before 7.0.2 (fixed in 7.0.2); version 7.1 only

Published 2026-05-01. Last modified 2026-06-17.