Cyber Resilience

CVE-2023-52556

Race Condition in Openbsd ≤ 7.4

Race Condition
Published
01 March 2024
Modified
10 October 2025
Patch / advisory
View advisory
CVSS Score v3.1 6.2
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.0014 4th percentile
Risk Priority 45 floored blend · peak EPSS

Summary

CVE-2023-52556 is a medium-severity Time-of-check Time-of-use (TOCTOU) Race Condition (CWE-367) vulnerability in Openbsd Openbsd. Its CVSS base score is 6.2 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Path Interception (T1034); ranked at the 4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-25 (Reference Monitor) and AC-3 (Access Enforcement) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

In OpenBSD 7.4 before errata 009, a race condition between pf(4)'s processing of packets and expiration of packet states may cause a kernel panic.

CWE(s)
CWE-367

Related Threats

MITRE ATT&CK Enterprise Techniques

T1034 Path Interception Persistence
**This technique has been deprecated.
attack.mitre.org →
T1548 Abuse Elevation Control Mechanism Privilege Escalation
Adversaries may circumvent mechanisms designed to control privilege elevation to gain higher-level permissions.
attack.mitre.org →
T1574 Hijack Execution Flow Stealth
Adversaries may execute their own malicious payloads by hijacking the way operating systems run programs.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-40216Same product: Openbsd Openbsd
CVE-2024-11149Same product: Openbsd Openbsd
CVE-2024-10934Same product: Openbsd Openbsd
CVE-2026-56099Same product: Openbsd Openbsd
CVE-2023-52557Same product: Openbsd Openbsd
CVE-2024-11148Same product: Openbsd Openbsd
CVE-2026-41285Same product: Openbsd Openbsd
CVE-2023-52558Same product: Openbsd Openbsd
CVE-2023-27567Same product: Openbsd Openbsd
CVE-2026-55706Same product: Openbsd Openbsd

Affected Assets

openbsd
openbsd
7.4 · ≤ 7.4

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V15.4.2
  • V17.2.6

Mitigating Controls (NIST 800-53 r5) AI

AC-25 Reference Monitor good match

A reference monitor that is always invoked and analyzable structurally eliminates the non-atomic check-then-use pattern underlying TOCTOU.

AC-3 Access Enforcement partial match

Access enforcement that performs an atomic check-and-use decision directly stops the window in which a TOCTOU race can be exploited.

SC-39 Process Isolation partial match

Process isolation limits the blast radius of a successful TOCTOU exploitation but does not remove the race itself.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly include coding standards and reviews that prevent TOCTOU race conditions.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.17 Clock synchronization none match
none

Reliable, synchronized time across systems narrows the exploitable window in which a resource state can change between a security check and its use.

References