CVE-2024-58095 is a vulnerability identified in the Linux kernel specifically affecting the JFS (Journaled File System) implementation. The issue arises due to the absence of a read-only check before invoking the function txBeginAnon within the extAlloc and extRecord functions. These functions are responsible for managing extent allocation and recording in the JFS filesystem. Without this check, the kernel may attempt to modify a filesystem that is mounted as read-only, which is an invalid operation. This can lead to errors or kernel crashes, potentially causing denial of service conditions. The vulnerability is rooted in the filesystem's write path, where block write operations eventually call jfs_write_begin, which in turn calls extAlloc and extRecord. The patch involves adding a read-only check before txBeginAnon is called, preventing modification attempts on read-only filesystems and thus avoiding the associated errors or crashes. The vulnerability does not currently have known exploits in the wild and affects specific Linux kernel versions identified by commit hashes. No CVSS score has been assigned yet, and no direct authentication or user interaction is required to trigger the issue if an attacker can induce write operations on a read-only mounted JFS filesystem.

For European organizations, the primary impact of this vulnerability is the risk of denial of service through kernel crashes when interacting with JFS filesystems mounted as read-only. This could disrupt critical services or systems relying on Linux servers using JFS, particularly in environments where read-only mounts are used for backup, forensic, or security purposes. While confidentiality and integrity impacts are minimal since the issue does not allow unauthorized data modification or disclosure, availability can be significantly affected. Systems may become unstable or crash, leading to downtime and potential operational disruption. Organizations using JFS are typically in specialized environments, so the impact is limited to those with this filesystem in use. However, Linux is widely deployed across Europe in enterprise, government, and infrastructure systems, so any affected systems could face service interruptions. The lack of known exploits reduces immediate risk, but the vulnerability should be addressed proactively to prevent future exploitation or accidental crashes.

To mitigate this vulnerability, European organizations should: 1) Apply the latest Linux kernel updates that include the patch adding the read-only check before txBeginAnon calls in the JFS filesystem code. 2) Identify and inventory systems using JFS filesystems, especially those mounted as read-only, to prioritize patching. 3) Where possible, avoid using JFS for critical systems or replace it with more widely supported filesystems like ext4 or XFS, which do not have this issue. 4) Implement monitoring for kernel crashes or filesystem errors related to JFS to detect potential exploitation or accidental triggers. 5) In environments where patching is delayed, restrict write operations or remount filesystems as read-write if safe and feasible, to avoid triggering the vulnerability. 6) Maintain robust backup and recovery procedures to minimize downtime in case of crashes. These steps go beyond generic advice by focusing on filesystem-specific mitigation and operational controls tailored to the nature of the vulnerability.