Cato Networks macOS Client Vulnerability Enables Low-Privilege Code Execution

A critical vulnerability in Cato Networks’ widely used macOS VPN client has been disclosed, enabling attackers with limited access to gain full control over affected systems.

Tracked as ZDI-25-252 (CVE pending), the flaw highlights mounting risks for enterprises relying on remote-access tools in hybrid work environments.

Security firm Zero Day Initiative (ZDI) uncovered the bug, which carries a CVSS score of 7.8 and allows local privilege escalation via Cato’s “Helper” service.

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Attackers could exploit it to execute arbitrary code with root privileges, effectively bypassing macOS security safeguards.

Vulnerability Breakdown

The flaw stems from a Time-of-Check to Time-of-Use (TOCTOU) race condition in the Cato Client’s installation process.

Improper locking mechanisms let low-privileged users manipulate package installations mid-execution.

Key Technical Details:

• Attack Vector: Local access required (physical or via compromised user account).
• Impact: Full system compromise (confidentiality, integrity, and availability breaches).
• Affected Versions: All Cato Client for macOS builds prior to April 2025.

ZDI’s advisory reveals a rocky disclosure process:

• March 12, 2025: Vulnerability reported via Cato’s portal.
• April 15, 2025: ZDI announced intent to publish as a zero-day after no patch emerged.
• April 23, 2025: Coordinated public release.

As of publication, Cato Networks has not released an official fix or advisory.

The company’s silence raises concerns, given its client’s adoption by Fortune 500 firms and government agencies.

Mitigation and Best Practices

While enterprises await a patch, ZDI and cybersecurity experts recommend:

1. Restrict Local Access: Enforce strict user privilege policies and multi-factor authentication.
2. Monitor Helper Services: Use endpoint detection tools to flag anomalous process spawning.
3. Prepare for Updates: Apply Cato’s upcoming patch immediately upon release.

This marks the fourth privilege escalation flaw in enterprise VPN clients since 2023, per ZDI data.

With macOS dominating 34% of the corporate desktop market (IDC, 2024), the stakes for supply-chain security have never been higher.

Cato Networks faces mounting pressure to address the gap as threat actors likely reverse-engineer the exploit. Organizations using the client should:

• Audit deployment logs for unusual activity.
• Consider temporary network segmentation for macOS devices.
• Review ZDI’s full advisory (ZDI-25-252) for IOC detection guidance.

For now, the incident reinforces a critical axiom: even trusted security tools can become attack vectors if vigilance lapses.

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