External risk intelligence

FreeBSD UMTX Shared Memory Incorrect Reference Count Leading to Kernel Panic or Sandbox Escape.

CVE advisorySeverity: CRITICAL (CVSS 10.0)

CVE-2024-43102

The vulnerability exists in the kernel-level UMTX shared memory management mechanism. Exploitation requires local, unprivileged access to the system to invoke specific system calls. It is not exposed to the public internet by design in normal deployment patterns and is not a service that receives network traffic.

Use After Free

Freebsd

13.0 to before 13.313.313.414.014.1

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

This advisory addresses a critical vulnerability in FreeBSD's shared memory management that could allow an attacker with local access to crash the system or potentially execute code. The issue arises from how the system handles concurrent requests to destroy shared memory mappings, leading to a condition where memory is freed too early. While exploitation requires local access, the potential impact on system stability and security is significant, necessitating an understanding of its relevance to our FreeBSD deployments.

Local users could crash the system.
Critical vulnerability impacts system stability.
Confirm relevance to FreeBSD systems.

Attack Path

How an attacker could exploit the issue

An attacker with the ability to run code on the system could trigger this vulnerability by making concurrent requests to destroy shared memory mappings. This could lead to a system crash or potentially allow for more advanced attacks, including code execution or escaping security restrictions.

Requires local code execution access.
Triggers via parallel shared memory destruction calls.
Risks kernel panic or arbitrary code execution.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could affect the stability of a FreeBSD system, potentially leading to a kernel panic. Under specific conditions, it may also enable advanced attacks like code execution or the escape from security sandboxes.

Kernel stability and integrity.
Concurrent system calls trigger memory issues.
System crashes or unauthorized code execution.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability affects the FreeBSD kernel's shared memory management. Ownership typically lies with the infrastructure or platform teams responsible for the operating system, with initial triage by security teams. The first practical move is to identify all FreeBSD systems, confirm their exposure and criticality, and then engage the relevant platform or system owners to plan remediation, potentially coordinating with the FreeBSD vendor for patched releases or workarounds.

Platform/Infrastructure teams own resolution.
Verify FreeBSD systems and exposure.
Plan and coordinate OS patching.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is FreeBSD?

FreeBSD is an open-source operating system designed for high performance, stability, and networking. It is widely used to power internet infrastructure, web servers, storage platforms, and embedded devices. The kernel acts as the core manager of system resources, including shared memory, which is the component affected by this vulnerability.

What does CVE-2024-43102 mean?

This is a memory management vulnerability involving the Use-After-Free weakness class. It occurs when the kernel incorrectly handles concurrent requests to destroy shared memory mappings. Because the system frees the memory too early while it is still in use, the kernel can become unstable, potentially leading to a system crash, unauthorized code execution, or an escape from security restrictions like Capsicum sandboxes.

How is this vulnerability triggered?

An attacker must be able to execute code on the target system to trigger the bug. By issuing specific, parallel system calls to destroy shared memory, they force the kernel to miscalculate reference counts. Simply interacting with standard applications or services that use shared memory does not trigger this issue; it requires deliberate, malicious use of the UMTX_SHM_DESTROY function.

Is my FreeBSD system at risk?

According to Halo Surface Signal, this vulnerability is not exposed to the public internet by design. It requires local, unprivileged access to the system to invoke the necessary commands. While technically classified as having a network-based component in the CVSS score, it is not a service that receives external network traffic, making remote exploitation highly unlikely in standard deployments.

What should I do to secure my systems?

Identify all servers running the affected versions of FreeBSD to establish your footprint. Once identified, coordinate with your platform or infrastructure teams to schedule operating system updates. The primary response involves applying the patches provided by the FreeBSD vendor to resolve the kernel-level memory management flaw.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.