CVE-2024-53206 is a high-severity use-after-free vulnerability in the Linux kernel's TCP stack, specifically within the reqsk_timer_handler() function that manages TCP request sockets. The flaw arises due to improper handling of request socket references during timer expiration and retry attempts. The vulnerable code incorrectly passes the 'req' pointer to reqsk_put() instead of the original 'oreq' pointer, leading to a use-after-free condition when the request socket (reqsk) is migrated but a retry attempt fails, such as due to a timeout. This use-after-free can result in memory corruption, potentially allowing an attacker to execute arbitrary code with kernel privileges, cause denial of service through kernel crashes, or escalate privileges. The vulnerability is tracked under CWE-416 (Use After Free). The fix involved replacing inet_csk_reqsk_queue_drop_and_put() with separate calls to __inet_csk_reqsk_queue_drop() and reqsk_put(), ensuring the correct pointer (oreq) is passed to reqsk_put() to prevent premature freeing of memory. The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity, requiring local privileges but no user interaction. The vulnerability affects multiple Linux kernel versions identified by specific commit hashes. No known exploits are currently reported in the wild, but the nature of the flaw and its kernel-level impact make it a critical patching priority for affected systems.

For European organizations, this vulnerability poses significant risks due to the widespread use of Linux in enterprise servers, cloud infrastructure, and embedded systems. Exploitation could lead to full system compromise, allowing attackers to bypass security controls, access sensitive data, disrupt critical services, or pivot within networks. Sectors such as finance, healthcare, telecommunications, and government, which rely heavily on Linux-based infrastructure, could face operational disruptions and data breaches. The vulnerability's requirement for local privileges means that attackers would need some level of access, but once achieved, the impact could be severe. Given the kernel-level nature, successful exploitation could undermine the integrity and availability of critical systems, potentially affecting compliance with European data protection regulations such as GDPR. Additionally, denial of service conditions could impact service availability, affecting business continuity.

European organizations should prioritize patching affected Linux kernel versions as soon as vendor updates become available, ensuring that the fix replacing inet_csk_reqsk_queue_drop_and_put() with the correct handling is applied. System administrators should audit their environments to identify vulnerable kernel versions using the provided commit hashes or vendor advisories. Employing kernel live patching solutions can reduce downtime during remediation. Restricting local access to trusted users and implementing strict access controls can reduce the risk of exploitation. Monitoring system logs and kernel messages for anomalies related to TCP request socket handling may provide early detection of exploitation attempts. Additionally, organizations should maintain up-to-date intrusion detection and prevention systems capable of identifying suspicious kernel-level activities. For environments where patching is delayed, consider isolating vulnerable systems and limiting network exposure to reduce attack surface.