CVE-2026-31409Network attack vector

Cross-session lookup via uncleared binding state

Published Apr 6, 2026 · Updated Apr 6, 2026

Improper state handling in Linux Kernel ksmbd allows remote authenticated users to trigger cross-session lookup over SMB. The SMB2 session-setup error path leaves conn->binding set after a failed binding request, so ksmbd_session_lookup_all() falls back to the global sessions table. A multichannel SMB binding failure is required; later requests on that connection can resolve unrelated authenticated sessions by identifier.

CVSS severity8.8
High
EPSS probability0.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper state handling in Linux Kernel ksmbd allows remote authenticated users to trigger cross-session lookup over SMB. The SMB2 session-setup error path leaves conn->binding set after a failed binding request, so ksmbd_session_lookup_all() falls back to the global sessions table. A multichannel SMB binding failure is required; later requests on that connection can resolve unrelated authenticated sessions by identifier.

The record

CVE
CVE-2026-31409
Published
Apr 6, 2026
Updated
Apr 6, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1210
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 6, 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 <282343cf8a4a5a3603b1cb0e17a7083e4a593b03
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6260fc85ed1298a71d24a75d01f8b2e56d489a60
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6ebef4a220a1ebe345de899ebb9ae394206fe921
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <89afe5e2dbea6e9d8e5f11324149d06fa3a4efca
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <9feb2d1bf86d9e5e66b8565f37f8d3a7d281a772
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d073870dab8f6dadced81d13d273ff0b21cb7f4e

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <282343cf8a4a5a3603b1cb0e17a7083e4a593b03; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6260fc85ed1298a71d24a75d01f8b2e56d489a60; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6ebef4a220a1ebe345de899ebb9ae394206fe921; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <89afe5e2dbea6e9d8e5f11324149d06fa3a4efca; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <9feb2d1bf86d9e5e66b8565f37f8d3a7d281a772; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d073870dab8f6dadced81d13d273ff0b21cb7f4e

Published CVSS scores

8.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1210Exploitation of Remote Services

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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