---
id: CVE-2026-98870
title: 'ksmbd: remove stale channels from all sessions on teardown'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ksmbd: remove stale channels from all sessions on teardown

  ksmbd_sessions_deregister() removes a connection's channels from other
  sessions' channel lists only while co…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= b1b6ed903a6e2b3505a48706bcd499b447ef9e44 <
    f8200bb4994e65a2e5c5b314789eeae39078619d
  - >-
    Linux >= 47b018dba6ec7ebf403fd2d1e713bc7acc9bbb23 <
    9cd6d714d3ca0cff296542dc989696884e41970f
  - >-
    Linux >= 9ef4dfd5edbd02f4bf10cd420a30896093d98a67 <
    b145f9b56c87f9c23ad5464ab0844dbc1de12b36
  - >-
    Linux >= 5a5b0b7a01fe19b383b3c046546b5ae30c1a7d71 <
    a15cae16f4432a5ad919ee633e31b07178492955
  - >-
    Linux >= faf8578c77f3d846aca9cd882c293e03eafcc6df <
    b10665730fbf6b5e45fe422badcbbc3f0df96ef5
  - Linux e632f21a8bc0c59abc4960482836ac3782db93c0
  - Linux >= 5.15.222 < 5.16
  - Linux
published: '2026-10-23'
updated: '2026-10-24'
sourceUpdated: '2026-10-24T14:09:26.805Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98870'
references:
  - url: 'https://git.kernel.org/stable/c/f8200bb4994e65a2e5c5b314789eeae39078619d'
  - url: 'https://git.kernel.org/stable/c/9cd6d714d3ca0cff296542dc989696884e41970f'
  - url: 'https://git.kernel.org/stable/c/b145f9b56c87f9c23ad5464ab0844dbc1de12b36'
  - url: 'https://git.kernel.org/stable/c/a15cae16f4432a5ad919ee633e31b07178492955'
  - url: 'https://git.kernel.org/stable/c/b10665730fbf6b5e45fe422badcbbc3f0df96ef5'
tags:
  - cve.org
epss: 0.0025
epssPercentile: 0.15509
ingestedAt: '2026-10-23T13:24:55.586Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: remove stale channels from all sessions on teardown

ksmbd_sessions_deregister() removes a connection's channels from other
sessions' channel lists only while conn->binding is still set:

	if (conn->binding) {
		hash_for_each_safe(sessions_table, ...)
			ksmbd_chann_del(conn, sess);
	}

conn->binding is a transient flag: it is cleared once a binding
SESSION_SETUP completes, and also by a subsequent non-binding
SESSION_SETUP on the same connection (a reauthentication on a bound
channel, or a new SessionId==0 setup). A connection that has bound a
channel into another session's ksmbd_chann_list and then clears
conn->binding leaves that channel behind when it disconnects: the
channel, whose chann->conn points at the now freed struct ksmbd_conn,
stays on the owner session's list.

When the owning connection later tears down, the second loop
dereferences the stale channel:

	xa_for_each(&sess->ksmbd_chann_list, chann_id, chann)
		if (chann->conn != conn)
			ksmbd_conn_set_exiting(chann->conn);   /* freed */

which is a use-after-free write into the freed ksmbd_conn (the same
stale channel is also walked by show_proc_session() through /proc). The
session is leaked as well, because its channel list never empties.

Remove the conn->binding gate so a connection always removes its
channels from every session on teardown.

## Affected

- `Linux >= b1b6ed903a6e2b3505a48706bcd499b447ef9e44 < f8200bb4994e65a2e5c5b314789eeae39078619d`
- `Linux >= 47b018dba6ec7ebf403fd2d1e713bc7acc9bbb23 < 9cd6d714d3ca0cff296542dc989696884e41970f`
- `Linux >= 9ef4dfd5edbd02f4bf10cd420a30896093d98a67 < b145f9b56c87f9c23ad5464ab0844dbc1de12b36`
- `Linux >= 5a5b0b7a01fe19b383b3c046546b5ae30c1a7d71 < a15cae16f4432a5ad919ee633e31b07178492955`
- `Linux >= faf8578c77f3d846aca9cd882c293e03eafcc6df < b10665730fbf6b5e45fe422badcbbc3f0df96ef5`
- `Linux e632f21a8bc0c59abc4960482836ac3782db93c0`
- `Linux >= 5.15.222 < 5.16`
- `Linux`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.