CVE-2022-49349 is a high-severity use-after-free vulnerability in the Linux kernel's ext4 filesystem implementation, specifically within the ext4_rename_dir_prepare function. The ext4 filesystem is widely used in Linux environments, including servers, desktops, and embedded systems. The vulnerability arises due to improper handling of directory entries during a rename operation on directories. The root cause is that ext4_get_first_dir_block does not sufficiently validate directory entries after reading a directory block, allowing a malformed directory entry with an excessively large record length (rec_len) to cause an illegal parent directory entry reference. This leads to a use-after-free condition when ext4_rename_dir_prepare attempts to access freed memory, as detected by Kernel Address Sanitizer (KASAN). The vulnerability can result in kernel memory corruption, causing system instability, crashes (denial of service), or potentially arbitrary code execution with kernel privileges if exploited. The CVSS 3.1 score is 7.8 (high), reflecting the vulnerability's impact on confidentiality, integrity, and availability, with low attack complexity and requiring low privileges but no user interaction. The vulnerability affects multiple versions of the Linux kernel prior to the patch and is triggered by filesystem operations involving renaming directories on ext4 filesystems. The fix involves adding checks in ext4_get_first_dir_block to validate directory entries and triggering ext4_error() if directory entries are missing or corrupted, preventing the use-after-free scenario.

For European organizations, this vulnerability poses a significant risk due to the widespread use of Linux servers and infrastructure running ext4 filesystems. Exploitation could lead to system crashes or kernel-level compromise, impacting critical services such as web hosting, cloud infrastructure, and enterprise applications. Confidentiality breaches are possible if attackers gain kernel-level code execution, potentially accessing sensitive data or escalating privileges. Integrity and availability are also at risk, as attackers could disrupt operations or deploy persistent malware. Given the prevalence of Linux in government, finance, telecommunications, and industrial control systems across Europe, the impact could be severe, especially in sectors requiring high availability and data protection. The vulnerability does not require user interaction but does require local privileges, so insider threats or compromised accounts could leverage this flaw. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, as weaponization is feasible.

European organizations should promptly apply Linux kernel updates that include the patch for CVE-2022-49349. Since the vulnerability requires local privileges, strict access controls and user privilege management are critical to reduce the attack surface. Implement mandatory access controls (e.g., SELinux, AppArmor) to limit filesystem operation capabilities. Regularly audit and monitor filesystem integrity and kernel logs for suspicious rename operations or ext4 errors. Employ kernel hardening techniques such as Kernel Address Sanitizer (KASAN) in testing environments to detect similar issues early. For critical systems where immediate patching is challenging, consider isolating vulnerable systems or restricting access to trusted users only. Backup important data regularly to mitigate potential data loss from crashes or exploitation. Finally, maintain up-to-date intrusion detection systems tuned to detect abnormal filesystem activity patterns.