CVE-2024-0775 is a use-after-free vulnerability identified in the ext4 filesystem code of the Linux kernel, specifically within the __ext4_remount function located in fs/ext4/super.c. The flaw arises when the kernel attempts to remount an ext4 filesystem and frees old quota file names before a potential failure, leading to a use-after-free condition. This memory mismanagement can cause an information leak, as the freed memory may still be accessed or referenced, potentially exposing sensitive data or allowing further exploitation. The vulnerability requires local user access with high privileges (PR:H) but does not require user interaction (UI:N). The CVSS 3.1 vector (AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H) indicates that the attack vector is local, with low attack complexity, and that the vulnerability impacts confidentiality, integrity, and availability to a high degree. Although no known exploits are currently reported in the wild, the nature of the flaw suggests that an attacker with sufficient privileges could leverage it to escalate privileges or cause system instability. The vulnerability affects all versions of the Linux kernel using ext4 filesystem code prior to the patch. Given the widespread use of ext4 as the default filesystem in many Linux distributions, this vulnerability has broad implications for systems relying on Linux for critical operations.

For European organizations, the impact of CVE-2024-0775 could be significant, especially for those running Linux servers and infrastructure that utilize the ext4 filesystem. The vulnerability allows a local attacker with elevated privileges to cause information leaks and potentially corrupt system memory, which could lead to privilege escalation or denial of service. This could compromise sensitive data confidentiality and system integrity, affecting sectors such as finance, healthcare, government, and critical infrastructure. Organizations relying on Linux-based cloud services or on-premises servers are at risk, particularly if local access controls are weak or if multiple users share system access. The potential for disruption to availability also raises concerns for service continuity. Although exploitation requires local privileged access, insider threats or attackers who gain initial footholds could leverage this vulnerability to deepen their access and cause further damage.

To mitigate CVE-2024-0775, European organizations should prioritize applying official Linux kernel patches as soon as they become available from trusted sources such as distribution vendors (e.g., Red Hat, Debian, Ubuntu). Until patches are deployed, organizations should restrict local privileged access to trusted users only and implement strict access controls and monitoring to detect suspicious activity. Employing mandatory access controls (e.g., SELinux, AppArmor) can help limit the impact of exploitation. Regularly auditing user privileges and system logs can identify potential exploitation attempts early. Additionally, organizations should ensure that backup and recovery procedures are robust to quickly restore systems in case of compromise. For environments where patching is delayed, consider isolating critical systems or using virtualization/containerization to limit exposure. Finally, educating system administrators about this vulnerability and the importance of timely patching is essential.