CVE-2024-10459 is a use-after-free vulnerability classified under CWE-416 that occurs in the layout engine of Mozilla Firefox and Thunderbird when accessibility features are enabled. Use-after-free bugs happen when a program continues to use memory after it has been freed, leading to undefined behavior such as crashes or potentially exploitable conditions. In this case, the vulnerability can be triggered remotely by an attacker who entices a user to interact with malicious content, causing the browser or email client to access freed memory during layout processing with accessibility enabled. This results in a crash that impacts application availability. The vulnerability affects Firefox versions earlier than 132, Firefox ESR versions earlier than 128.4 and 115.17, and Thunderbird versions earlier than 128.4 and 132. The CVSS v3.1 base score is 6.5, reflecting a medium severity with network attack vector, low attack complexity, no privileges required, but requiring user interaction. The impact is limited to availability (denial of service) with no direct confidentiality or integrity compromise. No public exploits have been reported yet, but the flaw could be leveraged for denial-of-service attacks or potentially more advanced exploitation if combined with other vulnerabilities. Mozilla has published the vulnerability details but no patch links are currently provided, indicating that fixes may be forthcoming or in progress.

For European organizations, this vulnerability primarily poses a risk of denial-of-service through application crashes in Firefox and Thunderbird clients, especially in environments where accessibility features are enabled by default or required by users. This can disrupt business operations, particularly in sectors relying heavily on these applications for communication and web access, such as government, finance, healthcare, and critical infrastructure. Although the vulnerability does not directly compromise data confidentiality or integrity, repeated crashes could degrade user productivity and potentially be used as part of a broader attack strategy to cause operational disruption. Organizations with strict accessibility compliance requirements may have a larger attack surface. The lack of known exploits reduces immediate risk, but the medium severity score and ease of triggering the bug via user interaction warrant timely mitigation to avoid service interruptions.

European organizations should monitor Mozilla’s official channels for patches addressing CVE-2024-10459 and apply updates promptly once available. Until patches are released, organizations can mitigate risk by disabling accessibility features in Firefox and Thunderbird where feasible, especially for users not requiring these features. Employing endpoint protection solutions that monitor for abnormal application crashes and suspicious activity can help detect exploitation attempts. User education to avoid interacting with untrusted or suspicious web content or email can reduce exposure. Network-level protections such as web filtering and email scanning should be enhanced to block malicious payloads targeting this vulnerability. Additionally, organizations should maintain robust incident response plans to quickly address any service disruptions caused by exploitation attempts.