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CVE Record

CVE-2026-43377: ksmbd: Don't log keys in SMB3 signing and encryption key generation

In the Linux kernel, the following vulnerability has been resolved: ksmbd: Don't log keys in SMB3 signing and encryption key generation When KSMBD_DEBUG_AUTH logging is enabled, generate_smb3signingkey() and generate_smb3encryptionkey() log the session, signing, encryption, and decryption key bytes. Remove the logs to avoid exposing credentials.

HighCVSS 8.1Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Linux's ksmbd SMB server could write sensitive SMB session and cryptographic keys into logs when authentication debugging was enabled. Anyone able to obtain those logs could potentially undermine protected SMB communications or sessions. Normal configurations without this debug logging are less likely to expose key material.

Executive priority

Prioritize affected internet-facing or sensitive-file SMB servers and any environment where debug logs are broadly collected or accessible. Patch promptly, disable the debug option, and investigate historical log exposure. Systems not using ksmbd or without this logging condition have lower immediate urgency.

Technical view

The affected ksmbd key-generation functions logged session, signing, encryption, and decryption key bytes when KSMBD_DEBUG_AUTH was enabled. The kernel fixes remove those log statements. The supplied CVSS 3.1 score is 8.1, reflecting high confidentiality and integrity impact without an availability impact.

Likely exposure

Exposure requires Linux systems using ksmbd, KSMBD_DEBUG_AUTH logging, relevant SMB key generation, and access to resulting logs. The supplied version data lists several affected kernel branches but does not clearly define every boundary; confirm the running distribution kernel against vendor guidance and the referenced stable fixes.

Exploitation context

The source bundle marks this CVE as absent from KEV and provides no evidence of active exploitation or a public exploit. Exploitation would likely depend on obtaining logs containing generated keys; the sources do not establish how attackers might gain that access.

Researcher notes

This is a secondary key-disclosure weakness rather than direct unauthenticated key extraction. Impact depends on debug configuration, log retention, and log-reader privileges. The duplicated commit identifier and broad version list in the supplied data make exact branch-level exposure uncertain; validate against distribution backports and the six referenced stable commits.

Mitigation direction

  • Identify Linux systems using in-kernel ksmbd and determine whether KSMBD_DEBUG_AUTH logging is enabled.
  • Apply vendor-supported kernel builds incorporating the referenced stable fixes.
  • Until patched, disable KSMBD_DEBUG_AUTH and tightly restrict access to kernel and service logs.
  • Treat accessible historical logs as sensitive and follow incident procedures for potential key exposure.

Validation and detection

  • Confirm the running kernel's vendor changelog or advisory includes the referenced ksmbd fix.
  • Verify KSMBD_DEBUG_AUTH logging is disabled unless specifically required and safely controlled.
  • Review retained logs and access records for unexpected access or exposed key material.
  • After remediation, confirm SMB signing and encryption still function without key bytes appearing in logs.
Prepared
Confidence
medium
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2026-43377 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.1 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
0ADP providers
7Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.1CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N2.85.2Linux

Vulnerability scoring details

Base CVSS 3.1 score

8.1High
CVSS 3.1 vector shape for CVE-2026-43377Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxe2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9unaffected
LinuxLinux5.15, 0, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.9, 7.0affected
Weakness

CWE details

No CWE listed

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