CVE-2026-98115: ksmbd: safely drain sessions during logoff
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: safely drain sessions during logoff
SMB3 multichannel allows requests for one session to run on multiple connections. Wait for all channels bound to a session before freeing shared session objects.
A deferred byte-range lock remains counted as a running request and only wakes when its file closes. Wake blocked locks during the drain without unpublishing or modifying their file objects. Synchronous CANCEL requests must invoke their cancellation callback to wake pending operations, while CHANGENOTIFY completion remains specific to the asynchronous path.
Serialize session teardown with channel registration and previous-session cleanup, and use atomic work-state transitions so LOGOFF, CANCEL, and connection teardown invoke cancellation callbacks only once.
Affected Software
Event History
Frequently Asked Questions
What configurations are exposed to this issue?
Systems using the Linux kernel's ksmbd SMB server with SMB3 multichannel sessions are exposed to the affected session-logoff handling. The issue involves requests for a single session running across multiple connections.
What can trigger the vulnerable teardown path?
Session LOGOFF, synchronous CANCEL requests, and connection teardown can trigger the relevant cancellation and session-draining paths. Deferred byte-range locks and pending operations can remain active while session objects are being freed.
What is the mitigation if an updated kernel cannot be deployed immediately?
The provided information does not specify a configuration workaround. Reducing or avoiding use of ksmbd SMB3 multichannel sessions would avoid the specific multi-channel condition described, but the data does not state whether this is a complete mitigation.