CVE-2026-31476

HIGH

ksmbd: do not expire session on binding failure

Title source: cna
STIX 2.1

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: do not expire session on binding failure When a multichannel session binding request fails (e.g. wrong password), the error path unconditionally sets sess->state = SMB2_SESSION_EXPIRED. However, during binding, sess points to the target session looked up via ksmbd_session_lookup_slowpath() -- which belongs to another connection's user. This allows a remote attacker to invalidate any active session by simply sending a binding request with a wrong password (DoS). Fix this by skipping session expiration when the failed request was a binding attempt, since the session does not belong to the current connection. The reference taken by ksmbd_session_lookup_slowpath() is still correctly released via ksmbd_user_session_put().

Scores

CVSS v3 8.2
EPSS 0.0025
EPSS Percentile 48.7%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Details

Status published
Products (23)
Linux/Linux < 5.15
Linux/Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 - 1d1888b4a7aec518b707f6eca0bf08992c0e8da3
Linux/Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 - 6fafc4c4238e538969f1375f9ecdc6587c53f1cc
Linux/Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 - 9bbb19d21ded7d78645506f20d8c44895e3d0fb9
Linux/Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 - a897064a457056acb976e20e3007cdf553de340f
Linux/Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 - e0e5edc81b241c70355217de7e120c97c3429deb
Linux/Linux 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 - f5300690c23c5ac860499bb37dbc09cf43fd62e6
Linux/Linux 5.15
Linux/Linux 6.1.168 - 6.1.*
Linux/Linux 6.12.80 - 6.12.*
... and 13 more
Published Apr 22, 2026
Tracked Since Apr 22, 2026