CVE-2024-27058 is a medium-severity race condition vulnerability in the Linux kernel's tmpfs filesystem implementation, specifically related to the handling of disk quota (dquot) information stored in a red-black tree (rb_tree). The flaw arises due to improper synchronization when accessing and modifying the root node of the dquot rb_tree. The vulnerability was discovered via a syzkaller reproducer, which identified a race condition during concurrent operations that remove or manipulate dquot entries. The root cause is that fetching the rb_tree root node is not adequately protected by the dqio_sem semaphore. Without this protection, concurrent threads can cause the root node to change between the time it is fetched and when the search for a specific node begins. This leads to a scenario where shmem_release_dquot() fails to find the expected node, triggering warnings and potentially causing inconsistent state or memory corruption. The race involves two threads: one attempting to release a dquot and another acquiring or releasing dquots, with the latter performing a tree rebalance while holding the dqio_sem semaphore. The vulnerability affects Linux kernel versions identified by the given commit hashes and was publicly disclosed on May 1, 2024. The CVSS 3.1 base score is 4.7 (medium), reflecting network attack vector, low attack complexity, high privileges required, no user interaction, unchanged scope, and low impact on confidentiality, integrity, and availability. No known exploits are currently reported in the wild. The issue was addressed by ensuring that fetching the rb_tree root node is also protected by dqio_sem, preventing the race condition and ensuring consistent tree traversal and modification.

For European organizations, this vulnerability poses a moderate risk primarily to systems running affected Linux kernel versions with tmpfs and disk quota features enabled. The vulnerability could lead to kernel warnings, potential instability, or memory corruption, which may cause denial of service or unpredictable behavior on critical infrastructure servers, cloud environments, or container hosts. Since the attack complexity is low but requires high privileges, exploitation would likely be limited to insiders or attackers who have already gained elevated access. However, successful exploitation could undermine system integrity and availability, impacting services reliant on tmpfs for temporary storage or quota enforcement. Organizations operating Linux-based servers in sectors such as finance, telecommunications, government, and critical infrastructure should be aware of this vulnerability. While no active exploits are known, the presence of a race condition in kernel memory management is a concern for system reliability and security posture. The medium severity rating suggests that while immediate widespread impact is unlikely, patching is important to prevent potential escalation or exploitation in multi-tenant or shared environments common in European data centers and cloud providers.

European organizations should prioritize applying the official Linux kernel patches that address CVE-2024-27058 as soon as they become available from their Linux distribution vendors. Beyond patching, system administrators should audit and monitor tmpfs usage and disk quota configurations to detect unusual kernel warnings or errors related to dquot handling. Employing kernel live patching solutions where available can reduce downtime during remediation. Restricting privileged access to systems and enforcing strict access controls will limit the risk of exploitation, given the high privilege requirement. Additionally, organizations should implement robust kernel logging and alerting to identify race condition symptoms early. For environments using containers or virtual machines, ensuring that host kernels are updated is critical, as container escapes or privilege escalations could leverage this vulnerability. Finally, testing patches in staging environments before production deployment will help avoid unintended disruptions.