CVE-2025-43229 is a vulnerability classified under CWE-79 (Improper Neutralization of Input During Web Page Generation, commonly known as Cross-Site Scripting) affecting Apple Safari browser. The root cause is improper state management when processing certain crafted web content, which allows an attacker to inject and execute arbitrary JavaScript code within the context of any website loaded in Safari. This universal cross-site scripting (UXSS) flaw can bypass same-origin policy protections, enabling attackers to steal cookies, session tokens, or other sensitive information, and potentially manipulate the content displayed to the user. The vulnerability requires no privileges and can be triggered remotely by enticing a user to visit a maliciously crafted webpage, thus requiring user interaction. The issue was addressed by Apple in macOS Sequoia 15.6 and Safari 18.6 through improved state management mechanisms that prevent the malicious script injection. The CVSS v3.1 base score is 6.1, reflecting medium severity with network attack vector, low attack complexity, no privileges required, but user interaction necessary. No public exploits have been reported yet, but the potential for abuse exists given Safari's widespread use. The vulnerability affects unspecified versions prior to the patch, so organizations must verify their Safari versions and update accordingly.

For European organizations, this vulnerability poses a risk primarily to confidentiality and integrity of web sessions and data accessed via Safari. Attackers exploiting this flaw could hijack user sessions, steal authentication tokens, or manipulate web content to conduct phishing or fraud. Sectors relying heavily on web applications accessed through Safari, such as finance, government, healthcare, and critical infrastructure, could face targeted attacks. The impact is heightened in environments where Safari is a standard browser, including macOS and iOS users within enterprises. Although availability is not directly affected, the breach of confidentiality and integrity can lead to significant operational and reputational damage. The requirement for user interaction limits automated exploitation but does not eliminate risk, especially in phishing-prone environments. The absence of known exploits currently provides a window for proactive mitigation. Failure to patch could lead to increased targeted attacks leveraging this UXSS vulnerability.

1. Immediately update all Apple devices to macOS Sequoia 15.6 and Safari 18.6 or later versions where the vulnerability is fixed. 2. Enforce strict Content Security Policy (CSP) headers on web applications to restrict the execution of unauthorized scripts, reducing the impact of potential UXSS attacks. 3. Educate users about the risks of clicking on untrusted links or visiting suspicious websites, as exploitation requires user interaction. 4. Employ browser security features such as Intelligent Tracking Prevention and sandboxing to limit script capabilities. 5. Monitor network traffic and endpoint logs for unusual web activity that could indicate attempted exploitation. 6. For organizations with managed Apple devices, use Mobile Device Management (MDM) solutions to enforce timely patch deployment and browser configuration policies. 7. Conduct regular security assessments and penetration tests focusing on web application security and browser vulnerabilities. 8. Consider deploying web filtering solutions to block access to known malicious URLs and phishing sites. These steps go beyond generic advice by focusing on layered defenses specific to UXSS in Safari and organizational user behavior.