CVE-2026-98870 (GCVE-0-2026-98870)

Vulnerability from cvelistv5 – Published: 2026-10-23 11:37 – Updated: 2026-10-23 11:37
VLAI
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 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.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7061 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: b1b6ed903a6e2b3505a48706bcd499b447ef9e44 , < f8200bb4994e65a2e5c5b314789eeae39078619d (git)
Affected: 47b018dba6ec7ebf403fd2d1e713bc7acc9bbb23 , < 9cd6d714d3ca0cff296542dc989696884e41970f (git)
Affected: 9ef4dfd5edbd02f4bf10cd420a30896093d98a67 , < b145f9b56c87f9c23ad5464ab0844dbc1de12b36 (git)
Affected: 5a5b0b7a01fe19b383b3c046546b5ae30c1a7d71 , < a15cae16f4432a5ad919ee633e31b07178492955 (git)
Affected: faf8578c77f3d846aca9cd882c293e03eafcc6df , < b10665730fbf6b5e45fe422badcbbc3f0df96ef5 (git)
Affected: e632f21a8bc0c59abc4960482836ac3782db93c0 (git)
Affected: 5.15.222 , < 5.16 (semver)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/mgmt/user_session.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
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              "versionType": "git"
            },
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              "versionType": "git"
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            },
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            }
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          "product": "Linux",
          "programFiles": [
            "fs/smb/server/mgmt/user_session.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux"
        }
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      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
            }
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        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: remove stale channels from all sessions on teardown\n\nksmbd_sessions_deregister() removes a connection\u0027s channels from other\nsessions\u0027 channel lists only while conn-\u003ebinding is still set:\n\n\tif (conn-\u003ebinding) {\n\t\thash_for_each_safe(sessions_table, ...)\n\t\t\tksmbd_chann_del(conn, sess);\n\t}\n\nconn-\u003ebinding is a transient flag: it is cleared once a binding\nSESSION_SETUP completes, and also by a subsequent non-binding\nSESSION_SETUP on the same connection (a reauthentication on a bound\nchannel, or a new SessionId==0 setup). A connection that has bound a\nchannel into another session\u0027s ksmbd_chann_list and then clears\nconn-\u003ebinding leaves that channel behind when it disconnects: the\nchannel, whose chann-\u003econn points at the now freed struct ksmbd_conn,\nstays on the owner session\u0027s list.\n\nWhen the owning connection later tears down, the second loop\ndereferences the stale channel:\n\n\txa_for_each(\u0026sess-\u003eksmbd_chann_list, chann_id, chann)\n\t\tif (chann-\u003econn != conn)\n\t\t\tksmbd_conn_set_exiting(chann-\u003econn);   /* freed */\n\nwhich is a use-after-free write into the freed ksmbd_conn (the same\nstale channel is also walked by show_proc_session() through /proc). The\nsession is leaked as well, because its channel list never empties.\n\nRemove the conn-\u003ebinding gate so a connection always removes its\nchannels from every session on teardown."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-23T11:37:07.113Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f8200bb4994e65a2e5c5b314789eeae39078619d"
        },
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          "url": "https://git.kernel.org/stable/c/9cd6d714d3ca0cff296542dc989696884e41970f"
        },
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          "url": "https://git.kernel.org/stable/c/b145f9b56c87f9c23ad5464ab0844dbc1de12b36"
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        },
        {
          "url": "https://git.kernel.org/stable/c/b10665730fbf6b5e45fe422badcbbc3f0df96ef5"
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      ],
      "title": "ksmbd: remove stale channels from all sessions on teardown",
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      }
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98870",
    "datePublished": "2026-10-23T11:37:07.113Z",
    "dateReserved": "2026-09-25T10:25:14.377Z",
    "dateUpdated": "2026-10-23T11:37:07.113Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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                "product": "Linux",
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                ],
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: remove stale channels from all sessions on teardown\n\nksmbd_sessions_deregister() removes a connection\u0027s channels from other\nsessions\u0027 channel lists only while conn-\u003ebinding is still set:\n\n\tif (conn-\u003ebinding) {\n\t\thash_for_each_safe(sessions_table, ...)\n\t\t\tksmbd_chann_del(conn, sess);\n\t}\n\nconn-\u003ebinding is a transient flag: it is cleared once a binding\nSESSION_SETUP completes, and also by a subsequent non-binding\nSESSION_SETUP on the same connection (a reauthentication on a bound\nchannel, or a new SessionId==0 setup). A connection that has bound a\nchannel into another session\u0027s ksmbd_chann_list and then clears\nconn-\u003ebinding leaves that channel behind when it disconnects: the\nchannel, whose chann-\u003econn points at the now freed struct ksmbd_conn,\nstays on the owner session\u0027s list.\n\nWhen the owning connection later tears down, the second loop\ndereferences the stale channel:\n\n\txa_for_each(\u0026sess-\u003eksmbd_chann_list, chann_id, chann)\n\t\tif (chann-\u003econn != conn)\n\t\t\tksmbd_conn_set_exiting(chann-\u003econn);   /* freed */\n\nwhich is a use-after-free write into the freed ksmbd_conn (the same\nstale channel is also walked by show_proc_session() through /proc). The\nsession is leaked as well, because its channel list never empties.\n\nRemove the conn-\u003ebinding gate so a connection always removes its\nchannels from every session on teardown."
          }
        ],
        "id": "CVE-2026-98870",
        "lastModified": "2026-10-23T12:18:20.397",
        "metrics": {},
        "published": "2026-10-23T12:18:20.397",
        "references": [
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



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