CVE-2026-43377Network attack vector

SMB3 session-key disclosure via authentication debug logging

Published May 8, 2026 · Updated May 8, 2026

Information disclosure in ksmbd in Linux Kernel allows remote authenticated users to expose SMB3 session keys via SMB3 session setup. generate_smb3signingkey() and generate_smb3encryptionkey() write session, signing, encryption, and decryption key bytes to kernel logs instead of excluding that material from diagnostic output. The leak requires KSMBD_DEBUG_AUTH logging and an authenticated SMB3 session with signing or encryption, exposing protected traffic without directly affecting availability.

CVSS severity8.1
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in ksmbd in Linux Kernel allows remote authenticated users to expose SMB3 session keys via SMB3 session setup. generate_smb3signingkey() and generate_smb3encryptionkey() write session, signing, encryption, and decryption key bytes to kernel logs instead of excluding that material from diagnostic output. The leak requires KSMBD_DEBUG_AUTH logging and an authenticated SMB3 session with signing or encryption, exposing protected traffic without directly affecting availability.

The record

CVE
CVE-2026-43377
Published
May 8, 2026
Updated
May 8, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1552.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 8, 2026CVE publishedPublication date reported by the CVE source.
  2. May 8, 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=5.15
  2. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <3fe2d9ec166b7df9a8df6c0fdcfc210572e27e3f
  3. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <407cc37c21d51f9b9d4d20204b04890880cfa6ae
  4. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <4084ed720d7d5f4e975c9e4a6267a552dad3b24a
  5. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <441336115df26b966575de56daf7107ed474faed
  6. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <c6b01b997a2094969e315f1ebfc1d64b8ae2163d
  7. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <fec5c70b82af3f59f15bb984df94e5ad1fccfb1e

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.15; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <3fe2d9ec166b7df9a8df6c0fdcfc210572e27e3f; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <407cc37c21d51f9b9d4d20204b04890880cfa6ae; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <4084ed720d7d5f4e975c9e4a6267a552dad3b24a; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <441336115df26b966575de56daf7107ed474faed; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <c6b01b997a2094969e315f1ebfc1d64b8ae2163d; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <fec5c70b82af3f59f15bb984df94e5ad1fccfb1e

Published CVSS scores

8.1kernel.orgCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1552.001Unsecured Credentials: Credentials In Files

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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