CVE-2023-38431Network attack vector

Unauthenticated kernel memory disclosure via malformed SMB lengths

Published Jul 17, 2023 · Updated Aug 2, 2024

Out-of-bounds read in Linux kernel ksmbd before 6.3.8 allows remote attackers to disclose kernel memory or crash the host via SMB. ksmbd_conn_handler_loop trusts pdu_size from the NetBIOS header without validating its relationship to the SMB header sizes, permitting reads beyond valid message data. The flaw is remotely reachable without authentication only when the in-kernel SMB server is enabled, and its bounded consequences are memory disclosure or service interruption.

CVSS severity9.1
Critical
EPSS probability1.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Linux kernel ksmbd before 6.3.8 allows remote attackers to disclose kernel memory or crash the host via SMB. ksmbd_conn_handler_loop trusts pdu_size from the NetBIOS header without validating its relationship to the SMB header sizes, permitting reads beyond valid message data. The flaw is remotely reachable without authentication only when the in-kernel SMB server is enabled, and its bounded consequences are memory disclosure or service interruption.

The record

CVE
CVE-2023-38431
Published
Jul 17, 2023
Updated
Aug 2, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-125, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1190Exploit Public-Facing Application

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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