CVE-2025-24140 is a vulnerability identified in Apple macOS where files downloaded from the internet may not have the mandatory quarantine attribute applied. The quarantine flag is a security feature that marks files as potentially unsafe, prompting macOS's Gatekeeper and other security subsystems to perform checks before allowing execution. The issue stems from improper state management within the file download handling process, causing the system to fail to assign this flag consistently. This flaw was addressed and resolved in macOS Sequoia 15.3 through improved state management. The vulnerability has a CVSS 3.1 base score of 5.3, reflecting a network attack vector with low attack complexity, no privileges required, and no user interaction needed. The impact is limited to integrity, as files lacking the quarantine flag might execute without security prompts, potentially allowing malicious code to run undetected. There is no evidence of active exploitation in the wild at the time of publication. The CWE associated with this vulnerability is CWE-276, which relates to improper handling of permissions or state. This vulnerability affects all macOS versions prior to 15.3, although the affectedVersions field is not explicitly detailed in the provided data. The absence of quarantine flags undermines macOS's layered security model, increasing the risk of malware execution from downloaded files.

The primary impact of this vulnerability is a reduction in the effectiveness of macOS's security controls, specifically Gatekeeper and related quarantine-based protections. Without the quarantine flag, downloaded files may execute without triggering security warnings or scans, increasing the risk of malware infections and unauthorized code execution. This can lead to integrity violations where malicious files run undetected, potentially compromising user systems. While confidentiality and availability are not directly impacted, the integrity compromise can facilitate further attacks such as persistence, privilege escalation, or data manipulation. Organizations with macOS endpoints, especially those in security-sensitive environments, face increased risk of malware infiltration. The lack of required user interaction and low attack complexity means attackers could exploit this vulnerability remotely by enticing users to download malicious files. However, the absence of known exploits in the wild suggests limited immediate risk but underscores the need for timely patching to prevent future exploitation.

To mitigate this vulnerability, organizations should prioritize upgrading all macOS systems to version Sequoia 15.3 or later, where the issue is fixed. Until patches are applied, administrators can implement additional endpoint security controls such as enhanced monitoring for execution of unquarantined files and stricter application whitelisting policies. Network-level defenses should be configured to block or flag suspicious downloads from untrusted sources. User education is critical to avoid downloading files from unverified websites or sources. Employing third-party antivirus and endpoint detection and response (EDR) solutions that do not solely rely on macOS quarantine flags can provide an additional layer of protection. Regular audits of file quarantine status and system logs can help detect anomalies. Finally, organizations should maintain robust backup and incident response plans to quickly recover from potential malware incidents stemming from this vulnerability.