CVE-2025-43229 is a medium-severity vulnerability affecting Apple Safari, specifically related to the processing of maliciously crafted web content that can lead to universal cross-site scripting (UXSS). This vulnerability arises from improper state management within the browser, allowing an attacker to inject and execute arbitrary scripts in the context of any website visited by the user. UXSS differs from traditional XSS in that it can bypass same-origin policy restrictions, potentially affecting all sites rendered by the browser rather than a single domain. The vulnerability was addressed by Apple through improved state management and fixed in macOS Sequoia 15.6 and Safari 18. The CVSS v3.1 base score is 6.1, indicating a medium severity level, with an attack vector of network (remote exploitation), low attack complexity, no privileges required, but user interaction is necessary (e.g., visiting a malicious webpage). The scope is changed, meaning the vulnerability affects resources beyond the initially vulnerable component. The impact affects confidentiality and integrity, allowing partial data disclosure and script injection, but does not impact availability. No known exploits are currently in the wild. CWE-79 (Improper Neutralization of Input During Web Page Generation) is the underlying weakness. This vulnerability poses a risk of session hijacking, credential theft, or unauthorized actions performed on behalf of the user if exploited.

For European organizations, this vulnerability presents a significant risk especially for those relying on Safari as a primary browser, including enterprises, government agencies, and critical infrastructure operators. Exploitation could lead to unauthorized access to sensitive information, session hijacking, and potential lateral movement within corporate networks if attackers leverage stolen credentials or session tokens. The universal nature of the XSS means that any website visited by the user could be leveraged for attack, increasing the attack surface. This is particularly concerning for sectors handling personal data under GDPR, as exploitation could lead to data breaches with regulatory and reputational consequences. Additionally, organizations with employees working remotely or using Safari on macOS devices are at risk. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits post-disclosure.

European organizations should prioritize updating to macOS Sequoia 15.6 and Safari 18 or later to apply the official patch from Apple. Until patching is possible, organizations should implement network-level protections such as web filtering to block access to known malicious sites and employ endpoint detection and response (EDR) solutions to monitor for suspicious browser behavior. User awareness training should emphasize caution when clicking on unknown links or visiting untrusted websites. Deploying Content Security Policy (CSP) headers on internal web applications can help mitigate the impact of XSS attacks. Organizations should also consider restricting the use of Safari in high-risk environments or enforcing browser usage policies that favor more secure browsers with robust sandboxing and security features. Regular vulnerability scanning and penetration testing should include checks for browser-based vulnerabilities. Finally, monitoring for unusual authentication or session activity can help detect exploitation attempts.