CVE-2022-49408 is a vulnerability identified in the Linux kernel's ext4 filesystem implementation, specifically within the function parse_apply_sb_mount_options(). The issue arises when the kernel processes on-disk mount options for ext4 filesystems. If the parsing of these mount options fails after memory has already been allocated in the ext4_fs_context structure (for example, in the s_qf_names field), the allocated memory is not properly freed, resulting in a memory leak. The root cause is that the code calls kfree() directly instead of using the ext4_fc_free() function, which is designed to correctly free all allocated resources in the ext4_fs_context. This improper memory management can lead to gradual memory exhaustion if the failure condition is triggered repeatedly. The vulnerability can be reproduced by formatting a device with ext4, setting specific mount options (such as usrjquota=file), mounting the device, and then using the kernel's kmemleak debug interface to detect the memory leak. Although this vulnerability does not directly allow code execution or privilege escalation, it can degrade system stability and availability by leaking memory in kernel space during mount operations. The flaw affects Linux kernel versions identified by the commit hashes listed, and it has been patched by correcting the memory free logic to use ext4_fc_free(). No known exploits are reported in the wild at this time, and no CVSS score has been assigned.

For European organizations, the impact of CVE-2022-49408 primarily concerns system stability and availability rather than confidentiality or integrity. Systems running Linux with ext4 filesystems that frequently mount or remount filesystems with specific mount options could experience memory leaks leading to resource exhaustion. This may cause degraded performance, system slowdowns, or even kernel panics in extreme cases, potentially disrupting critical services. Organizations relying on Linux servers for file storage, web hosting, or application deployment could face increased downtime or require more frequent reboots to clear leaked memory. While the vulnerability does not enable direct unauthorized access or data corruption, the indirect impact on availability could affect business continuity, especially in environments with high filesystem mount/unmount activity or automated scripts that manipulate mount options. Since ext4 is the default filesystem for many Linux distributions widely used across Europe, the vulnerability has broad relevance. However, the lack of known exploits and the requirement for specific mount option failures reduce the immediate risk level.

To mitigate CVE-2022-49408, European organizations should apply the latest Linux kernel updates that include the patch fixing the memory leak in parse_apply_sb_mount_options(). Kernel updates from trusted Linux distributors (such as Debian, Ubuntu, Red Hat, SUSE) should be prioritized and tested in staging environments before production deployment. Additionally, organizations should audit their use of ext4 mount options, avoiding or carefully validating any non-standard or experimental options that could trigger parsing failures. Monitoring kernel memory usage and employing tools like kmemleak can help detect abnormal memory leaks early. For systems with high mount/unmount frequency, consider implementing automated alerts for memory usage anomalies. In environments where immediate patching is not feasible, limiting the use of mount options that are known to cause parsing errors can reduce exposure. Finally, maintaining robust backup and recovery procedures ensures resilience against potential availability disruptions caused by this vulnerability.