CVE-2023-38429Network attack vector

Kernel memory corruption via undersized SMB allocation

Published Jul 17, 2023 · Updated Jan 3, 2025

Out-of-bounds access in Linux kernel KSMBD before 6.3.4 allows remote attackers to crash the system via a crafted SMB message. ksmbd_conn_handler_loop allocates the advertised PDU size plus the four-byte RFC 1002 header, although ksmbd_smb2_check_message accepts an additional implied bcc[0] byte. KSMBD must be enabled and reachable, and Ubuntu does not install its userspace tools by default; a kernel crash is established, while code execution remains possible.

CVSS severity9.8
Critical
EPSS probability1.18%
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 access in Linux kernel KSMBD before 6.3.4 allows remote attackers to crash the system via a crafted SMB message. ksmbd_conn_handler_loop allocates the advertised PDU size plus the four-byte RFC 1002 header, although ksmbd_smb2_check_message accepts an additional implied bcc[0] byte. KSMBD must be enabled and reachable, and Ubuntu does not install its userspace tools by default; a kernel crash is established, while code execution remains possible.

The record

CVE
CVE-2023-38429
Published
Jul 17, 2023
Updated
Jan 3, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-193, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 3, 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 National Vulnerability DatabaseCVSS: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.

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-193Off-by-one Error
T1499Endpoint Denial of Service

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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