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().
Published: 2026-04-22
Score: 8.2 High
EPSS: < 1% Very Low
KEV: No
Impact: Denial of Service via manipulation of SMB session expiration
Action: Patch Now
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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4561-1 linux-6.1 security update
Debian DSA Debian DSA DSA-6238-1 linux security update
Debian DSA Debian DSA DSA-6243-1 linux security update
History

Tue, 28 Apr 2026 21:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-400
CWE-640

Mon, 27 Apr 2026 23:30:00 +0000

Type Values Removed Values Added
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:o:linux:linux_kernel:5.15:-:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*

Mon, 27 Apr 2026 19:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-400
CWE-640

Mon, 27 Apr 2026 14:15:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 8.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H'}


Thu, 23 Apr 2026 00:15:00 +0000


Wed, 22 Apr 2026 14:15:00 +0000

Type Values Removed Values Added
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().
Title ksmbd: do not expire session on binding failure
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-05-11T22:09:28.365Z

Reserved: 2026-03-09T15:48:24.098Z

Link: CVE-2026-31476

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2026-04-22T14:16:44.337

Modified: 2026-04-27T23:25:16.793

Link: CVE-2026-31476

cve-icon Redhat

Severity :

Publid Date: 2026-04-22T00:00:00Z

Links: CVE-2026-31476 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-04-29T00:15:43Z

Weaknesses