CVE-2025-31258 is a sandbox escape vulnerability identified in Apple macOS, specifically addressed in the macOS Sequoia 15.5 update. The sandbox mechanism in macOS is designed to confine applications, restricting their ability to access system resources or other applications beyond defined boundaries. This vulnerability arises from a flaw in the sandbox implementation that could allow a malicious or compromised app to break out of its sandbox constraints. The vulnerability is classified under CWE-284 (Improper Access Control), indicating that the affected code failed to enforce proper access restrictions. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N) indicates that the vulnerability can be exploited remotely over the network without any privileges or user interaction, with low attack complexity. The impact primarily affects confidentiality and integrity, as an attacker could potentially access or modify data beyond the sandbox. Apple mitigated this issue by removing the vulnerable code in the latest macOS release. No known exploits have been reported in the wild, but the potential for sandbox escape makes this a significant concern for security-sensitive environments. The vulnerability affects all prior versions of macOS before Sequoia 15.5, although exact affected versions are not specified in the provided data.

If exploited, this vulnerability could allow malicious applications to escape the sandbox environment, thereby bypassing critical security controls that isolate apps and protect system integrity. This could lead to unauthorized access to sensitive data, modification of system or user files, and potentially facilitate further privilege escalation or lateral movement within the system. The breach of sandbox containment undermines the foundational security model of macOS, increasing the risk of persistent malware infections or data exfiltration. Organizations relying on macOS for critical operations, especially those handling sensitive or regulated data, could face confidentiality breaches and integrity violations. Although availability impact is rated as none, the loss of confidentiality and integrity can have severe operational and reputational consequences. The ease of exploitation (no privileges or user interaction required) increases the threat level, making timely patching essential to prevent potential attacks.

Organizations should immediately plan to update all macOS systems to version Sequoia 15.5 or later, where the vulnerable code has been removed. Until patching is complete, restrict installation of untrusted or unsigned applications to reduce the risk of malicious apps attempting sandbox escape. Employ application whitelisting and endpoint protection solutions that can detect anomalous behavior indicative of sandbox escape attempts. Monitor system logs and security alerts for unusual activity that might suggest exploitation attempts. Implement network segmentation to limit exposure of vulnerable systems and reduce the attack surface. For environments where immediate patching is not feasible, consider disabling or restricting features that allow installation or execution of third-party apps. Regularly review and update security policies to enforce least privilege and sandboxing principles. Finally, maintain awareness of any emerging exploit reports or indicators of compromise related to this vulnerability to respond promptly.