CVE-2023-38427Network attack vector

Remote crash or disclosure via misaligned length accounting

Published Jul 17, 2023 · Updated May 5, 2025

Out-of-bounds read in Linux kernel ksmbd before 6.3.8 allows remote attackers to crash systems or disclose kernel memory via SMB. In deassemble_neg_contexts, the bounds check measures an unpadded context length, but the loop subtracts a larger eight-byte-aligned step, underflowing the remaining-length counter and permitting an out-of-bounds read. The ksmbd server must be enabled and reachable for a crafted SMB negotiate-context sequence to trigger the crash or disclosure.

CVSS severity9.8
Critical
EPSS probability1.24%
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 crash systems or disclose kernel memory via SMB. In deassemble_neg_contexts, the bounds check measures an unpadded context length, but the loop subtracts a larger eight-byte-aligned step, underflowing the remaining-length counter and permitting an out-of-bounds read. The ksmbd server must be enabled and reachable for a crafted SMB negotiate-context sequence to trigger the crash or disclosure.

The record

CVE
CVE-2023-38427
Published
Jul 17, 2023
Updated
May 5, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-191, CWE-125, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 17, 2023CVE publishedPublication date reported by the CVE source.
  2. May 5, 2025Record 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

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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

CWE-191Integer Underflow (Wrap or Wraparound)
CWE-125Out-of-bounds Read
T1499.004Application or System Exploitation

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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