ClearanceKit is a macOS security tool that intercepts file-system access events to enforce per-process access policies, thereby controlling which processes can access specific files. Prior to version 4.2.4, ClearanceKit failed to intercept two critical file operation event types: ES_EVENT_TYPE_AUTH_EXCHANGEDATA and ES_EVENT_TYPE_AUTH_CLONE. These event types represent specific file operations related to exchanging authorization data and cloning file descriptors or objects. Because these events were not routed through ClearanceKit's opfilter system extension, local processes with limited privileges could exploit this gap to bypass the file access policies enforced by ClearanceKit. This missing authorization check corresponds to CWE-862 (Missing Authorization). The vulnerability allows unauthorized local processes to access or manipulate files that should be restricted, potentially leading to unauthorized data disclosure or modification. The patch, introduced in commit 6181c4a, subscribes to these two event types and ensures they are evaluated by the existing policy enforcement mechanism. Users must upgrade to ClearanceKit version 4.2.4 or later and reactivate the system extension to apply the fix. The vulnerability has a CVSS 4.0 base score of 8.4, reflecting high severity due to the potential impact on confidentiality and integrity, ease of exploitation by local users, and limited scope requiring local access but no user interaction or authentication. No known exploits have been reported in the wild as of the publication date.

This vulnerability allows local processes on macOS systems running vulnerable versions of ClearanceKit to bypass file access policies, potentially leading to unauthorized access, modification, or disclosure of sensitive files. The impact is significant in environments where ClearanceKit is used to enforce strict file access controls, such as enterprise or government systems handling confidential data. Attackers with local access but limited privileges can escalate their capabilities by circumventing these controls, undermining the confidentiality and integrity of protected files. Although the vulnerability does not directly affect availability, the unauthorized access could facilitate further attacks, including data exfiltration or privilege escalation. Organizations relying on ClearanceKit for endpoint security or compliance may face increased risk of data breaches or policy violations. The absence of known exploits in the wild reduces immediate risk but does not diminish the potential impact if exploited. The vulnerability is confined to macOS systems with ClearanceKit installed, limiting the scope but posing a high risk to affected environments.

To mitigate this vulnerability, organizations should immediately upgrade ClearanceKit to version 4.2.4 or later, which includes the patch subscribing to the missing event types and enforcing proper authorization. After upgrading, it is critical to reactivate the ClearanceKit system extension to ensure the new policy enforcement is operational. Additionally, organizations should audit local user privileges and restrict local access to trusted users only, minimizing the risk of exploitation by unauthorized local processes. Monitoring file access logs and system events for unusual activity related to ES_EVENT_TYPE_AUTH_EXCHANGEDATA and ES_EVENT_TYPE_AUTH_CLONE events can help detect attempts to exploit the vulnerability. Implementing endpoint detection and response (EDR) solutions that monitor for anomalous file access patterns on macOS can provide additional protection. Finally, organizations should maintain an up-to-date inventory of macOS systems running ClearanceKit to ensure timely patch deployment and compliance verification.