External risk intelligence

macOS Sandbox Escape Vulnerability Addressed in Sequoia and Tahoe

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-64731

The vulnerability requires a malicious application to be executed locally on the device to exploit a sandbox breakout. It is not reachable via the public internet or network services, as it is a client-side issue specific to local application execution and sandbox boundaries.

Path Traversal

Apple Macos

15.0 to before 15.7.826.0 to before 26.6

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

A path handling vulnerability in macOS has been fixed with improved validation. This issue could allow a malicious application to bypass security restrictions, potentially impacting data integrity and system availability. The main concern is confirming relevance and exposure to this vulnerability.

Malicious apps could escape security boundaries.
Protects user data and system integrity.
Confirm relevance and assess exposure.

Attack Path

How an attacker could exploit the issue

An attacker could leverage a malicious app to escape its sandbox by exploiting a path handling issue. This vulnerability requires a local application to be present and executable on the target system. Once triggered, this could allow the malicious app to gain unauthorized access to other parts of the operating system.

Local app execution required.
Triggered by path handling flaw.
Risk of sandbox escape.

Live Threat

Current exploitation, exposure, and threat context

A path handling flaw in macOS could allow a malicious application to escape its sandbox when supported by the advisory. This could expose system data and user data, potentially leading to unauthorized access or modification of information.

System data and user data at risk.
Malicious app may break sandbox.
Unauthorized access and modification.

Operational Fix

Recommended remediation, mitigation, and detection steps

Teams responsible for macOS endpoints, including IT operations and endpoint security, should prioritize addressing this vulnerability. The initial step involves identifying all macOS devices, confirming their reachability and business criticality, and locating the accountable system owner. Remediation planning should then be based on the assessed risk, considering factors like potential for sandbox escapes by malicious applications.

Identify macOS assets and owners.
Verify sandbox breakout exposure.
Plan risk-based remediation.

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 macOS Sequoia and Tahoe?

These are versions of the Apple macOS operating system. They provide the core software environment that manages hardware resources and runs applications. The sandbox feature within these operating systems is designed to isolate apps from one another and from sensitive system files to ensure that if an application is compromised, the rest of the system remains protected.

What is the nature of the CVE-2026-64731 vulnerability?

This vulnerability is classified as CWE-22, which involves improper limitation of a pathname to a restricted directory. In plain terms, it means the operating system fails to properly validate file paths. Because of this flaw, a malicious program can trick the system into accessing files or areas outside of its intended sandbox boundaries, effectively breaking the security wall meant to contain it.

How is this sandbox breakout triggered?

The vulnerability is triggered by the presence and execution of a malicious application on the device. It does not occur through normal usage or by simply viewing files. If the application is not present or cannot be executed, this specific path handling flaw remains inactive and the sandbox boundaries remain intact.

Do I need to worry about network attacks for this vulnerability?

According to Halo Surface Signal, this is considered a client-side issue, meaning it is very unlikely to be reachable via the public internet or remote network services. Because the flaw requires a malicious application to be running locally on the specific macOS device to attempt an escape, the primary focus should be on local application security rather than remote perimeter defenses.

Is there a recommended first step to respond to CVE-2026-64731?

The immediate priority is to identify all devices running affected versions of macOS Sequoia or Tahoe within your environment. Once your assets are identified and the system owners are located, you should plan to update to the patched versions provided by Apple to ensure the improved path validation is active, thereby closing the security gap that allows for potential sandbox escapes.

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.