CVE-2024-47701 is a vulnerability identified in the Linux kernel's ext4 filesystem implementation. The flaw arises when the extended attributes (xattr) data associated with a file or directory changes underneath the filesystem during an operation that looks up an entry in an inlined directory. Specifically, if the e_value_offs offset is modified by changes in the underlying block device, it can cause an out-of-bounds (OOB) memory access. This is detected by the Kernel Address Sanitizer (KASAN) as a use-after-free (UAF) error in the ext4_search_dir function. The vulnerability occurs because the ext4 filesystem does not properly validate the consistency of xattr data after it has been read, leading to potential memory corruption. The issue is triggered when the filesystem is mounted without a journal and quota mode is disabled, as indicated in the example scenario. The kernel call trace shows the fault occurs during directory entry lookup and symlink creation operations, which rely on ext4's inline directory and xattr handling. The vulnerability can lead to kernel crashes or potentially arbitrary code execution if exploited, due to the memory corruption caused by the UAF. The fix involves adding a validity check for xattrs immediately after reading the inode, preventing the use of stale or corrupted xattr data. This vulnerability affects Linux kernel versions prior to the patch that addresses this issue, specifically those around the 6.11.0-rc4 release candidate referenced in the report. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2024-47701 can be significant, especially for those relying heavily on Linux-based infrastructure using the ext4 filesystem. The ext4 filesystem is widely deployed across servers, cloud environments, and embedded systems in Europe. Exploitation of this vulnerability could lead to kernel crashes causing denial of service (DoS), which can disrupt critical services and business operations. More critically, the use-after-free condition could be leveraged by a skilled attacker to execute arbitrary code with kernel privileges, potentially leading to full system compromise. This poses risks to confidentiality, integrity, and availability of data and services. Organizations running containerized workloads, virtual machines, or cloud services on Linux hosts are particularly at risk, as attackers could escape container boundaries or escalate privileges. The lack of authentication or user interaction requirements for triggering the vulnerability increases the attack surface. Given Europe's strong regulatory environment around data protection (e.g., GDPR), a successful attack exploiting this vulnerability could also result in compliance violations and reputational damage. The absence of known exploits currently provides a window for proactive mitigation, but the vulnerability's nature demands urgent attention.

European organizations should prioritize patching Linux kernels to the latest stable versions that include the fix for CVE-2024-47701. Since the vulnerability is related to ext4 filesystem handling, kernel updates from trusted Linux distributions (Debian, Ubuntu, Red Hat, SUSE, etc.) should be applied promptly. For systems where immediate patching is not feasible, organizations should consider the following mitigations: 1) Avoid mounting ext4 filesystems without journaling enabled, as the vulnerability is demonstrated in non-journaled mounts; enabling journaling can reduce risk. 2) Implement strict access controls and monitoring on systems with ext4 filesystems to detect unusual filesystem activity or kernel errors indicative of exploitation attempts. 3) Use kernel hardening features such as KASAN, Kernel Page Table Isolation (KPTI), and SELinux/AppArmor policies to limit the impact of potential exploits. 4) Restrict untrusted users' ability to create or modify extended attributes or symlinks on ext4 filesystems. 5) Employ runtime integrity monitoring and kernel crash analysis tools to quickly identify exploitation attempts. 6) In virtualized or containerized environments, isolate workloads and limit privileges to reduce the blast radius of a potential kernel compromise. 7) Maintain up-to-date backups and incident response plans to recover quickly from any successful attacks.