CVE-2025-43518 is a logic-based vulnerability within the spellcheck API of Apple macOS, identified in 2025. The flaw stems from inadequate validation checks in the API, which could allow a malicious or compromised application to access files it should not be authorized to read. This represents a breach of the intended security boundaries enforced by macOS, potentially exposing sensitive user or system data. The vulnerability was addressed by Apple through improved validation logic in macOS Sonoma 14.8.3 and macOS Sequoia 15.7.3, indicating that earlier versions remain vulnerable. The lack of a CVSS score suggests the vulnerability was newly disclosed and not yet fully assessed, but the nature of unauthorized file access implies significant risk. No public exploits have been reported, which may indicate limited exploitation or recent patch availability. The vulnerability does not require user interaction beyond app installation, but it does require that a malicious app be present on the system, highlighting the importance of application control. The affected versions are unspecified, but any macOS version prior to the patched releases should be considered at risk. This vulnerability could be leveraged to exfiltrate sensitive files or escalate privileges within the system, impacting confidentiality and potentially integrity. The spellcheck API is a common system service, so the attack surface is broad for any macOS user or organization running vulnerable versions.

For European organizations, this vulnerability poses a significant confidentiality risk as unauthorized file access could lead to exposure of sensitive corporate or personal data. Organizations relying on macOS devices, especially in sectors like finance, technology, and government, may face data breaches or intellectual property theft if exploited. The vulnerability could be used to bypass normal file access controls, undermining endpoint security. Since the exploit requires a malicious app, organizations with less stringent application vetting or BYOD policies are at higher risk. The impact extends to potential regulatory consequences under GDPR if personal data is compromised. Additionally, the breach of file confidentiality could facilitate further attacks, such as lateral movement or privilege escalation. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits post-disclosure. The patch availability mitigates risk if promptly applied, but delayed updates increase exposure. Overall, the vulnerability could disrupt business operations, damage reputation, and incur financial losses if exploited.

European organizations should prioritize immediate patching of all macOS devices to versions Sonoma 14.8.3 or Sequoia 15.7.3 or later. Implement strict application control policies to prevent installation of unauthorized or untrusted apps, reducing the likelihood of malicious app presence. Employ endpoint detection and response (EDR) solutions capable of monitoring unusual file access patterns or API misuse related to spellcheck services. Conduct regular audits of installed applications and permissions to identify and remove potentially risky software. Educate users about the risks of installing unverified applications and enforce least privilege principles. Utilize Mobile Device Management (MDM) tools to enforce patch compliance and application restrictions across the organization. Monitor security advisories from Apple and update incident response plans to include this vulnerability. For sensitive environments, consider network segmentation to limit data accessible from compromised endpoints. Finally, maintain robust data encryption and backup strategies to mitigate data loss or exfiltration consequences.