CVE-2026-98870
Received
Received - Intake
ksmbd Channel Use-After-Free on Session Teardown
Vulnerability report for CVE-2026-98870, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-23
Last updated on: 2026-10-23
Assigner: kernel.org
Description
Description
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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| Linux | Linux | b1b6ed903a6e2b3505a48706bcd499b447ef9e44 |
| Linux | Linux | 47b018dba6ec7ebf403fd2d1e713bc7acc9bbb23 |
| Linux | Linux | 9ef4dfd5edbd02f4bf10cd420a30896093d98a67 |
| Linux | Linux | 5a5b0b7a01fe19b383b3c046546b5ae30c1a7d71 |
| Linux | Linux | faf8578c77f3d846aca9cd882c293e03eafcc6df |
| Linux | Linux | e632f21a8bc0c59abc4960482836ac3782db93c0 |
| Linux | Linux | 5.15.222 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
