CVE-2024-40789 is an out-of-bounds access vulnerability classified under CWE-125 that affects Apple Safari and related Apple operating systems. The root cause is insufficient bounds checking when processing certain web content, which can lead to accessing memory outside the intended buffer. This results in an unexpected process crash, causing a denial of service condition. The vulnerability affects Safari on iOS, iPadOS, macOS Sonoma, watchOS, tvOS, and visionOS, with fixes released in Safari 17.6 and OS updates such as iOS 16.7.9 and macOS 14.6. The CVSS 3.1 base score is 6.5 (medium severity), reflecting that the attack vector is network-based with low attack complexity, no privileges required, but user interaction is necessary (the user must visit a malicious web page). The impact is limited to availability, with no confidentiality or integrity loss reported. No known exploits have been observed in the wild, but the vulnerability could be leveraged by attackers to disrupt services or user experience by crashing Safari processes. This type of vulnerability is often used in targeted denial of service attacks or as part of a multi-stage exploit chain, although no such chaining is currently documented.

For European organizations, the primary impact is availability disruption on Apple devices running vulnerable versions of Safari and related OSes. This can affect employees’ productivity, especially in environments heavily reliant on Apple hardware and Safari for web access. Critical sectors such as finance, healthcare, and government could experience service interruptions if attackers exploit this vulnerability to crash browsers en masse or target specific users. While no data confidentiality or integrity loss is indicated, repeated crashes could lead to user frustration, potential loss of session data, or interruption of web-based applications. Organizations with remote or hybrid workforces using Apple devices are particularly at risk. Additionally, denial of service attacks could be used as a distraction or part of a larger attack campaign. The lack of known exploits reduces immediate risk, but the medium severity score and ease of exploitation mean timely patching is essential to prevent future exploitation.

European organizations should immediately deploy the Apple security updates that address CVE-2024-40789, including Safari 17.6 and OS updates iOS/iPadOS 16.7.9, macOS Sonoma 14.6, watchOS 10.6, tvOS 17.6, and visionOS 1.3. Ensure all managed Apple devices are updated promptly through centralized device management solutions like Apple Business Manager or Mobile Device Management (MDM) platforms. Educate users to avoid clicking on suspicious or untrusted web links, as exploitation requires user interaction. Implement network-level protections such as web filtering and DNS filtering to block access to known malicious sites. Monitor for unusual browser crashes or service disruptions that could indicate exploitation attempts. For critical environments, consider restricting Safari usage or enforcing alternative browsers until patches are applied. Maintain up-to-date incident response plans to quickly address potential denial of service incidents. Finally, keep abreast of threat intelligence updates for any emerging exploits targeting this vulnerability.