CVE-2024-39472 is a vulnerability in the Linux kernel's XFS filesystem implementation related to log recovery buffer allocation. The issue stems from how the kernel handles the h_size value, which is part of the log header size used during recovery of the XFS filesystem journal. Initially, a commit (a70f9fe52daa) introduced a fixup for incorrect h_size values set by older versions of the mkfs tool, which created the filesystem. This fixup was intended to handle legacy filesystems with malformed h_size values. However, a subsequent commit (0c771b99d6c9) cleaned up the calculation of log recovery buffer sizes but stopped using the fixed-up h_size value for sizing the log recovery buffer. This regression means that if an invalid h_size value is encountered—especially one crafted by a fuzzer rather than legacy mkfs tools—the kernel may allocate an incorrectly sized buffer for log recovery. This can lead to an out-of-bounds memory access during the recovery process. Such memory corruption issues can potentially be exploited to cause denial of service (kernel panic) or, in more severe cases, privilege escalation or arbitrary code execution within the kernel context. The vulnerability affects Linux kernel versions containing the specified commit hashes prior to the fix. The fix involves explicitly recalculating the log recovery buffer size by incorporating the corrected h_size value, preventing out-of-bounds access. No known exploits are reported in the wild as of the publication date, and no CVSS score has been assigned yet.

For European organizations, this vulnerability poses a risk primarily to systems running Linux with XFS filesystems, which are common in enterprise environments, cloud infrastructure, and data centers. Exploitation could lead to system crashes or kernel panics, resulting in denial of service and potential data loss or corruption. In sensitive environments such as financial institutions, healthcare, and critical infrastructure, such disruptions could have significant operational and reputational impacts. If exploited for privilege escalation, attackers could gain kernel-level access, compromising system integrity and confidentiality. Given the widespread use of Linux servers in Europe, especially in cloud service providers, telecommunications, and government agencies, the vulnerability could be leveraged in targeted attacks or automated scanning campaigns once exploit code becomes available. The absence of known exploits currently limits immediate risk, but the technical nature of the flaw and its location in kernel code handling filesystem recovery make it a high-value target for attackers aiming at persistent footholds or disruptive attacks.

European organizations should prioritize updating their Linux kernels to versions containing the patch that fixes CVE-2024-39472. Since the vulnerability relates to kernel code, applying vendor-supplied kernel updates or recompiling kernels with the fix is essential. Organizations using custom or long-term support kernels should monitor vendor advisories closely and apply backported patches promptly. Additionally, organizations should audit their use of XFS filesystems and consider temporary mitigations such as restricting access to systems with XFS volumes to trusted users and networks, minimizing exposure to untrusted inputs that could trigger the vulnerability. Implementing kernel lockdown features and mandatory access controls (e.g., SELinux, AppArmor) can reduce the risk of exploitation. Monitoring system logs for unusual kernel errors or crashes related to XFS recovery can help detect attempted exploitation. Finally, organizations should maintain robust backup and recovery procedures to mitigate potential data loss from denial of service or corruption.