CVE-2026-84559 in macOS
Summary
by MITRE • 09/15/2026
A permissions issue was addressed with improved validation. This issue is fixed in macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7. A malicious application may be able to access restricted files.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described involves a critical failure in the operating system's permission validation mechanisms within Apple's macOS ecosystem, specifically affecting versions prior to macOS Golden Gate 27, macOS Sequoia 15.8, and macOS Tahoe 26.7. This flaw represents a breakdown in the principle of least privilege, allowing processes that should be restricted from accessing certain sensitive areas of the file system to bypass these controls. The root cause lies in insufficient validation logic during access control checks, which permits malicious applications to read or potentially modify files that are designated as protected by the operating system's security architecture. This type of issue is commonly categorized under CWE-269 Improper Privilege Management and CWE-732 Incorrect Permission Assignment for Critical Resource, highlighting a fundamental failure in enforcing intended access restrictions.
From an operational perspective, this vulnerability poses significant risks to user privacy and data integrity. A malicious application exploiting this flaw could gain unauthorized access to sensitive personal files such as documents, photos, messages, or system configuration files that are typically shielded from standard applications by macOS sandboxing policies and entitlements. The ability to read restricted files can lead to information disclosure, where attackers harvest credentials, financial data, or private communications for subsequent exploitation in phishing campaigns or identity theft. Furthermore, if the vulnerability allows write access to critical system resources, it could facilitate persistence mechanisms or lateral movement within a compromised environment by modifying configuration files that control security settings or application behavior.
The attack vector typically involves social engineering tactics where users are tricked into installing and executing a malicious payload disguised as legitimate software. Once executed, the malware attempts to traverse directories protected by macOS's strict permission models, such as those managed through Gatekeeper, Notarization, or specific entitlements like com.apple.security.files.user-selected.read-write. Due to the validation flaw, these access requests are erroneously granted, bypassing the expected security boundaries. This aligns with MITRE ATT&CK techniques related to Data from Local System (T1005) and potentially T1083 File and Directory Discovery, as the attacker enumerates and extracts valuable data without triggering standard alerts associated with permission denials.
Mitigation strategies primarily involve immediate software updates to ensure that all macOS devices are running versions 27 of Golden Gate, 15.8 of Sequoia, or 26.7 of Tahoe, where Apple has implemented improved validation logic to correct the permissions handling error. Administrators should enforce strict application control policies using tools like Mobile Device Management (MDM) profiles that restrict execution of unsigned code and limit file system access based on predefined entitlements. Additionally, users should be educated about the risks of installing software from untrusted sources and encouraged to review app permissions regularly through System Settings. Regular auditing of installed applications and monitoring for anomalous file access patterns can also help detect potential exploitation attempts before significant data loss occurs.