CVE-2025-43400 is a vulnerability identified in Apple macOS and related Apple operating systems including macOS Sonoma 14.8.1, macOS Tahoe 26.0.1, macOS Sequoia 15.7.1, visionOS 26.0.1, iOS 26.0.1, iPadOS 26.0.1, iOS 18.7.1, and iPadOS 18.7.1. The vulnerability arises from an out-of-bounds write issue during the processing of font files. Specifically, when the system processes a maliciously crafted font, it may lead to unexpected application termination or corruption of process memory. This type of vulnerability typically results from improper bounds checking in the font parsing code, allowing data to be written outside the allocated memory buffer. Such memory corruption can cause application crashes (denial of service) or potentially be leveraged for arbitrary code execution if exploited further. However, as of the current information, no known exploits are reported in the wild. The vulnerability affects multiple Apple OS versions, indicating a widespread impact across Apple’s ecosystem. Apple has addressed this issue by improving bounds checking in the affected components, and patches have been released in the specified OS versions. The vulnerability does not have an assigned CVSS score yet, but the nature of the flaw suggests it could be leveraged for memory corruption attacks if combined with additional exploitation techniques. The vulnerability requires processing of a malicious font, which could be delivered via email attachments, web content, or other document formats that support embedded fonts. User interaction may be required to open or render the malicious font, but no authentication is needed to trigger the vulnerability once the font is processed by the system.

For European organizations, this vulnerability poses a risk primarily to users and systems running vulnerable Apple operating systems. The impact includes potential denial of service through application crashes, which could disrupt business operations or user productivity. More critically, if exploited in conjunction with other vulnerabilities or techniques, it could lead to arbitrary code execution, allowing attackers to execute malicious code with the privileges of the affected application. This could result in data breaches, unauthorized access, or persistence within the network. Given the widespread use of Apple devices in European enterprises, especially in sectors like finance, technology, and creative industries, the vulnerability could be leveraged in targeted attacks or phishing campaigns delivering malicious fonts. The lack of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially as threat actors often develop exploits after public disclosure. Organizations relying on Apple devices for critical operations should consider this vulnerability significant due to the potential for memory corruption and the broad attack surface presented by font processing.

European organizations should prioritize the following mitigation steps: 1) Deploy the official patches provided by Apple immediately to all affected devices, including macOS, iOS, iPadOS, and visionOS systems. 2) Implement strict email and web filtering to block or quarantine documents containing embedded fonts from untrusted or unknown sources. 3) Educate users about the risks of opening unsolicited attachments or links, particularly those that may contain embedded fonts or documents. 4) Utilize endpoint protection solutions capable of detecting anomalous behavior related to font processing or memory corruption attempts. 5) Monitor logs and system behavior for signs of crashes or unusual application terminations that could indicate exploitation attempts. 6) Where possible, restrict the use of applications that automatically process fonts from untrusted sources or sandbox such applications to limit potential damage. 7) Maintain an up-to-date inventory of Apple devices and ensure timely patch management processes are in place to reduce exposure windows.