CVE-2023-52558Network attack vector

Unauthenticated kernel panic via premature mbuf alignment

Published Mar 1, 2024 · Updated Nov 19, 2024

Denial of service in OpenBSD 7.3 before errata 019 and 7.4 before errata 002 allows remote attackers to crash the kernel. In sys/kern/uipc_mbuf.c, m_split() calls m_align() before converting a newly allocated mbuf to reference an existing cluster; an mbuf larger than MLEN triggers an assertion failure and kernel panic. No authentication or user interaction is required, and successful triggering interrupts the entire system without reported data disclosure or modification.

CVSS severity7.5
High
EPSS probability0.70%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in OpenBSD 7.3 before errata 019 and 7.4 before errata 002 allows remote attackers to crash the kernel. In sys/kern/uipc_mbuf.c, m_split() calls m_align() before converting a newly allocated mbuf to reference an existing cluster; an mbuf larger than MLEN triggers an assertion failure and kernel panic. No authentication or user interaction is required, and successful triggering interrupts the entire system without reported data disclosure or modification.

The record

CVE
CVE-2023-52558
Published
Mar 1, 2024
Updated
Nov 19, 2024
Vendor
OpenBSD Project
Product
OpenBSD
Classifications
CWE-131, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 1, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 19, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=7.3 <7.3 errata 019
  2. Affected versionversion=7.3 <7.3_errata_019
  3. Affected versionversion=7.4 <7.4 errata 002
  4. Affected versionversion=7.4 <7.4_errata_002

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OpenBSD Project · OpenBSDversion=7.3 <7.3 errata 019; version=7.3 <7.3_errata_019; version=7.4 <7.4 errata 002; version=7.4 <7.4_errata_002

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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.

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-131Incorrect Calculation of Buffer Size
T1499.004Application or System Exploitation

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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