CVE-2023-52556

Kernel panic via unsynchronized pf state timeout updates

Published Mar 1, 2024 · Updated Nov 14, 2024

Race condition in OpenBSD 7.4 before errata 009 allows local users to crash the kernel during pf packet-state processing. Packet paths update pf_state timeout values without holding the state mutex, allowing pf_test to write a timeout after pf_purge_expired_states marks the state PFTM_UNLINKED. The affected system must process packets through pf while a state expires; the resulting assertion failure causes a system-wide crash.

CVSS severity6.2
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in OpenBSD 7.4 before errata 009 allows local users to crash the kernel during pf packet-state processing. Packet paths update pf_state timeout values without holding the state mutex, allowing pf_test to write a timeout after pf_purge_expired_states marks the state PFTM_UNLINKED. The affected system must process packets through pf while a state expires; the resulting assertion failure causes a system-wide crash.

The record

CVE
CVE-2023-52556
Published
Mar 1, 2024
Updated
Nov 14, 2024
Vendor
OpenBSD Project
Product
OpenBSD
Classifications
CWE-367, CAPEC-29, T1499
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 1, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 14, 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=7.4 <7.4 errata 009

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

OpenBSD Project · OpenBSDversion=7.4 <7.4 errata 009

Published CVSS scores

6.2CISA-ADPCVSS:3.1/AV:L/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.

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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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
CAPEC-29Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions
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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