CVE-2026-20620 is a vulnerability identified in Apple macOS that stems from an out-of-bounds read condition, classified under CWE-125. This flaw arises due to insufficient input validation in the affected macOS kernel components, allowing an attacker to read memory outside the intended buffer boundaries. Such a memory disclosure can reveal sensitive kernel data, compromising system confidentiality. Additionally, the flaw can cause unexpected system termination, leading to denial of service. The vulnerability affects multiple macOS versions and has been addressed in the updates macOS Sequoia 15.7.4, macOS Tahoe 26.3, and macOS Sonoma 14.8.4. The CVSS v3.1 base score is 7.7, reflecting high severity, with the vector indicating local attack vector (AV:L), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), high confidentiality impact (C:H), no integrity impact (I:N), and high availability impact (A:H). Exploitation requires local access but no privileges or user interaction, making it a significant threat in environments where attackers can gain local presence. No public exploits are known yet, but the vulnerability's characteristics suggest it could be leveraged for privilege escalation or information disclosure attacks. The fix involves improved input validation to prevent out-of-bounds reads, thereby protecting kernel memory integrity and system stability.

The primary impact of CVE-2026-20620 is twofold: confidentiality breach and availability disruption. An attacker exploiting this vulnerability can read sensitive kernel memory, potentially exposing critical system information such as cryptographic keys, passwords, or other protected data, which could facilitate further attacks or privilege escalation. Additionally, causing unexpected system termination results in denial of service, disrupting normal operations and potentially affecting business continuity. Organizations relying on macOS systems, especially in sensitive environments like government, finance, healthcare, and technology sectors, face risks of data leakage and operational downtime. Since exploitation requires local access but no privileges or user interaction, insider threats or attackers who have gained initial foothold could leverage this vulnerability to escalate their capabilities or disrupt services. The absence of known exploits in the wild currently limits immediate widespread impact, but the vulnerability's high severity score and nature warrant urgent remediation to prevent future exploitation.

1. Apply the official patches released by Apple immediately: macOS Sequoia 15.7.4, macOS Tahoe 26.3, and macOS Sonoma 14.8.4 or later versions. 2. Restrict local access to macOS systems by enforcing strict physical security controls and limiting user accounts with local login privileges. 3. Implement endpoint detection and response (EDR) solutions capable of monitoring kernel-level anomalies, such as unusual memory reads or system crashes, to detect potential exploitation attempts. 4. Conduct regular audits of system logs to identify unexpected system terminations or suspicious activity indicative of exploitation. 5. Educate users and administrators about the risks of local access vulnerabilities and enforce the principle of least privilege to minimize attack surface. 6. For environments where immediate patching is not feasible, consider deploying temporary mitigations such as disabling unnecessary local services or restricting access via network segmentation to reduce the likelihood of local attacker presence. 7. Maintain up-to-date backups and incident response plans to quickly recover from potential denial of service caused by exploitation.