CVE-2026-74522
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk34th percentile - higher than 34% of all known CVEs
Summary
In the Linux kernel's SMB server (ksmbd), a use-after-free vulnerability was found in __close_file_table_ids(). A ksmbd_file can remain alive after logical close while another session holds a temporary reference. When the foreign holder performs the final put, the object is freed without being removed from its owner's idr, leading to a stale pointer dereference during file-table teardown.
Risk Assessment
The vulnerability can lead to kernel crash or potential code execution in kernel context, posing a serious threat to system integrity.
Recommendation
Apply the kernel patch that removes the volatile id from the owner's idr while holding the table lock and clears volatile_id before dropping the idr-owned reference. Update the system to a kernel version containing this fix.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free in __close_file_table_ids() A ksmbd_file can remain alive after logical close while another session holds a temporary reference obtained through ksmbd_lookup_fd_inode(). ksmbd_close_fd() currently marks the file closed and drops the idr-owned reference, but leaves the pointer published in the closing session's idr until the final reference is dropped. If the foreign holder performs the final ksmbd_fd_put(), __put_fd_final() supplies the foreign session's file table to __ksmbd_close_fd(). The object is then freed without being removed from its owner's idr, and the owner session later dereferences the stale pointer during file-table teardown. Remove the volatile id from the owner's idr while ksmbd_close_fd() still holds that table's lock, and clear volatile_id before dropping the idr-owned reference. A later foreign final put then only performs physical destruction and cannot remove the object from the wrong table.