Executive Summary

CVE-2026-40599 is a high-severity vulnerability in ClearanceKit versions up to 5.0.4. ClearanceKit intercepts file-system access events on macOS and enforces per-process access policies. The vulnerability arises because ClearanceKit incorrectly treats a process with an empty Team ID but a non-empty Signing ID as an Apple platform binary.

This flaw allows a malicious software to impersonate an Apple process in the global allowlist by creating an ad-hoc signed binary with a Signing ID present in the allowlist but without a valid Team ID. As a result, the malicious process can bypass security protections and access all protected files governed by ClearanceKit’s File Access Authorization rules.

The vulnerability requires local code execution with low privileges and no user interaction, and the attack complexity is low.

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Mitigation Strategies

The primary mitigation step is to upgrade ClearanceKit to version 5.0.5 or later, where this vulnerability is fixed.

Until the upgrade can be applied, restrict local code execution privileges to trusted users only, as exploitation requires local code execution with low privileges.

Review and tighten ClearanceKit’s configuration and global allowlist policies to minimize the risk of ad-hoc signed binaries being trusted.

Monitor system logs and ClearanceKit alerts for suspicious activity related to file access by processes with unusual signing attributes.

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Impact Analysis

This vulnerability can impact you by allowing a local attacker to bypass ClearanceKit’s security protections and gain unauthorized access to all protected files on the system.

The attacker can impersonate trusted Apple processes and read sensitive files that should normally be inaccessible, compromising the confidentiality and integrity of your data.

The vulnerability does not affect system availability but poses a significant risk to sensitive information stored on the device.

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Detection Guidance

This vulnerability involves ClearanceKit incorrectly treating processes with an empty Team ID and a non-empty Signing ID as Apple platform binaries, allowing unauthorized access. Detection involves identifying ad-hoc signed binaries that have a Signing ID present in ClearanceKit’s global allowlist but lack a valid Team ID.

To detect potential exploitation, you can look for processes running with suspicious Signing IDs that are ad-hoc signed (i.e., without a valid Team ID). On macOS, you might use commands to inspect the code signature and team ID of running processes.

• Use the `codesign` command to check the signing information of a binary: `codesign -dvvv /path/to/binary`
• Check the Team ID and Signing ID fields in the output to identify if the Team ID is empty but Signing ID is non-empty.
• Use `ps aux` or `pgrep` to list running processes and then inspect their binaries with `codesign`.
• Monitor file access events and ClearanceKit logs (if available) for unauthorized access attempts by processes with suspicious signing attributes.

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Compliance Impact

This vulnerability allows unauthorized local attackers to bypass ClearanceKit's protections and gain access to all protected files, impacting the confidentiality and integrity of sensitive data.

Such unauthorized access to sensitive files could lead to non-compliance with data protection regulations and standards like GDPR and HIPAA, which require strict controls over access to personal and protected health information.

By enabling attackers to impersonate trusted Apple processes and access protected files without proper authorization, the vulnerability undermines the enforcement of access policies critical for regulatory compliance.

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