CVE-2024-40866 is a vulnerability identified in Apple macOS Safari browser that enables an attacker to spoof the address bar when a user visits a maliciously crafted website. Address bar spoofing is a deceptive technique where the URL displayed in the browser’s address bar is manipulated to appear as a legitimate or trusted site, even though the actual content is controlled by an attacker. This can be exploited to conduct phishing attacks, tricking users into divulging sensitive information or credentials. The vulnerability does not require any privileges or authentication but does require user interaction in the form of visiting a malicious website. The flaw impacts the integrity of the user interface by misleading the user about the true origin of the web content. Apple addressed this issue by improving the UI protections in Safari 18 and macOS Sequoia 15, ensuring the address bar accurately reflects the loaded website. The CVSS 3.1 base score is 6.5 (medium severity), reflecting the lack of confidentiality impact but high integrity impact and ease of exploitation over the network without privileges. No known exploits have been reported in the wild, but the risk remains significant due to the potential for phishing and social engineering attacks leveraging this spoofing capability.

For European organizations, this vulnerability poses a significant risk primarily through phishing and social engineering attacks. Attackers can craft malicious websites that appear legitimate by spoofing the address bar, increasing the likelihood of users entering sensitive data such as login credentials, financial information, or confidential corporate data. This can lead to account compromise, unauthorized access to corporate resources, and potential data breaches. The integrity of user trust in web communications is undermined, which can have cascading effects on organizational security posture. Sectors such as finance, government, and critical infrastructure, which rely heavily on secure web communications and have high macOS usage, are particularly at risk. Although the vulnerability does not directly impact system availability or confidentiality, the indirect consequences of successful phishing attacks can be severe, including financial loss, reputational damage, and regulatory penalties under GDPR if personal data is compromised.

European organizations should prioritize updating all macOS devices to macOS Sequoia 15 and Safari to version 18 or later, where the vulnerability is fixed. Implement strict patch management policies to ensure timely deployment of these updates. Educate users about the risks of phishing and address bar spoofing, emphasizing the importance of verifying URLs and not trusting the address bar alone. Deploy advanced email and web filtering solutions to detect and block access to known malicious websites. Consider implementing multi-factor authentication (MFA) to reduce the impact of credential theft. Network-level protections such as DNS filtering and threat intelligence integration can help prevent users from reaching malicious sites. Regular security awareness training and simulated phishing exercises can improve user vigilance against such UI spoofing attacks. Finally, monitor for suspicious login activities and anomalous behavior that may indicate successful phishing exploitation.