CVE-2025-24140 is a vulnerability in Apple macOS related to the improper application of the quarantine flag on files downloaded from the internet. The quarantine flag is a key security feature that marks downloaded files as potentially unsafe, prompting macOS security services like Gatekeeper to perform checks before allowing execution. Due to a flaw in state management, certain downloaded files may not receive this flag, effectively bypassing these security controls. This vulnerability affects macOS versions prior to Sequoia 15.3, where Apple addressed the issue by improving state management to ensure the quarantine flag is correctly applied. The vulnerability is classified under CWE-276 (Incorrect Default Permissions), indicating a failure to set appropriate security attributes on files. The CVSS v3.1 base score is 5.3 (medium severity), with an attack vector of network (files downloaded from the internet), low attack complexity, no privileges required, no user interaction needed, and impact limited to integrity (potentially allowing malicious files to execute without warning). There are no known exploits in the wild, but the flaw could facilitate malware delivery by circumventing macOS's built-in defenses. This vulnerability primarily impacts the integrity of the system by allowing potentially malicious code to run without triggering quarantine-based protections. Organizations relying on macOS for critical operations should prioritize patching to prevent exploitation.

For European organizations, this vulnerability increases the risk of malware infections and unauthorized code execution on macOS endpoints. Since the quarantine flag triggers macOS security mechanisms like Gatekeeper and XProtect, its absence means that malicious files downloaded from the internet may execute without warning or scanning, potentially leading to compromise of user systems. This can result in data integrity issues, lateral movement within networks, and potential data breaches. Organizations with macOS-heavy environments, especially in sectors such as finance, technology, and government, may face elevated risks. The medium severity rating reflects that while the vulnerability does not directly impact confidentiality or availability, the integrity impact can facilitate further attacks. The lack of required privileges or user interaction lowers the barrier for exploitation, making it easier for attackers to deliver payloads via drive-by downloads or phishing campaigns. The absence of known exploits suggests limited current threat activity, but the vulnerability should be considered a significant risk until patched.

1. Upgrade all macOS systems to Sequoia 15.3 or later, where the vulnerability is fixed. 2. Enforce strict download policies restricting downloads from untrusted or unknown sources. 3. Implement endpoint protection solutions that do not solely rely on the quarantine flag but also scan files on download and execution. 4. Educate users about the risks of downloading and executing files from the internet, emphasizing caution even if no warnings appear. 5. Monitor network traffic for suspicious downloads and use network security tools to block known malicious sites. 6. Employ application whitelisting to restrict execution to approved software. 7. Regularly audit macOS security settings and quarantine flag behavior to detect anomalies. 8. Integrate macOS endpoint telemetry with centralized security monitoring to detect potential exploitation attempts. These steps go beyond generic patching by focusing on layered defenses and user awareness to mitigate risk during the window before full patch deployment.