CVE-2026-31476Network attack vector

Unauthenticated session invalidation via failed multichannel binding

Published Apr 22, 2026 · Updated Apr 22, 2026

Denial of service in Linux Kernel ksmbd allows remote attackers to invalidate active SMB sessions through a failed binding request. During binding, ksmbd_session_lookup_slowpath() returns another connection's target session, and the failure path wrongly marks that session SMB2_SESSION_EXPIRED. SMB3 multichannel and an active target session are required; a wrong-password binding request disconnects that session without user interaction.

CVSS severity8.2
High
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux Kernel ksmbd allows remote attackers to invalidate active SMB sessions through a failed binding request. During binding, ksmbd_session_lookup_slowpath() returns another connection's target session, and the failure path wrongly marks that session SMB2_SESSION_EXPIRED. SMB3 multichannel and an active target session are required; a wrong-password binding request disconnects that session without user interaction.

The record

CVE
CVE-2026-31476
Published
Apr 22, 2026
Updated
Apr 22, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1d1888b4a7aec518b707f6eca0bf08992c0e8da3
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6fafc4c4238e538969f1375f9ecdc6587c53f1cc
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <9bbb19d21ded7d78645506f20d8c44895e3d0fb9
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a897064a457056acb976e20e3007cdf553de340f
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e0e5edc81b241c70355217de7e120c97c3429deb
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f5300690c23c5ac860499bb37dbc09cf43fd62e6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1d1888b4a7aec518b707f6eca0bf08992c0e8da3; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6fafc4c4238e538969f1375f9ecdc6587c53f1cc; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <9bbb19d21ded7d78645506f20d8c44895e3d0fb9; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a897064a457056acb976e20e3007cdf553de340f; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e0e5edc81b241c70355217de7e120c97c3429deb; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f5300690c23c5ac860499bb37dbc09cf43fd62e6

Published CVSS scores

5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
8.2UbuntuCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
8.2Linux kernel CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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