CVE-2021-47088 is a use-after-free vulnerability identified in the Linux kernel's DAMON (Data Access Monitor) debugfs interface. Specifically, the issue arises in the kernel module responsible for monitoring memory access patterns, where synchronization between iteration and destruction of monitoring targets is flawed. The function dbgfs_target_ids_read() iterates over current monitoring targets while holding the kdamond_lock to ensure thread safety. However, the destruction of these targets in dbgfs_before_terminate() occurs without acquiring the same lock, leading to a race condition. This race condition can cause a use-after-free bug, where the system attempts to access memory that has already been freed. Exploiting this flaw could potentially lead to kernel crashes or undefined behavior, possibly enabling privilege escalation or denial of service. The vulnerability affects Linux kernel versions identified by the commit hash 4bc05954d0076655cfaf6f0135585bdc20cd6b11 and was publicly disclosed on March 4, 2024. The issue has been addressed by ensuring that the destruction of monitoring targets is protected by the kdamond_lock, eliminating the race condition. There are no known exploits in the wild at this time, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2021-47088 depends largely on their use of affected Linux kernel versions and whether they utilize the DAMON subsystem. Since DAMON is a specialized kernel feature used primarily for monitoring memory access patterns, typical enterprise Linux deployments may not have it enabled or exposed. However, organizations running custom Linux kernels, embedded systems, or specialized monitoring setups could be vulnerable. Successful exploitation could lead to kernel crashes resulting in denial of service or potentially privilege escalation if attackers can leverage the use-after-free to execute arbitrary code in kernel space. This could compromise confidentiality, integrity, and availability of critical systems. Given the widespread use of Linux in European data centers, cloud infrastructure, and embedded devices, unpatched systems could face operational disruptions or security breaches. The absence of known exploits reduces immediate risk, but the vulnerability should be treated seriously due to its kernel-level nature and potential for severe impact.

European organizations should promptly apply the official Linux kernel patches that address this vulnerability by protecting the destruction of DAMON monitoring targets with the kdamond_lock. System administrators should verify whether their Linux distributions have incorporated this fix and update kernels accordingly. For environments where kernel upgrades are challenging, consider disabling the DAMON subsystem if it is not required, thereby eliminating the attack surface. Additionally, organizations should implement strict access controls to debugfs interfaces to prevent unauthorized users from interacting with kernel debug features. Continuous monitoring for unusual kernel crashes or system instability can help detect exploitation attempts. Finally, maintain an up-to-date inventory of Linux kernel versions in use across all infrastructure to ensure timely patch management.