CVE-2024-53099 is a vulnerability identified in the Linux kernel related to the Berkeley Packet Filter (BPF) subsystem, specifically within the function bpf_link_show_fdinfo(). The issue arises when a newly added BPF link type does not invoke the macro BPF_LINK_TYPE(), which is responsible for properly registering and validating the link type. Without this invocation, the code attempts to access the bpf_link_type_strs array using an invalid or out-of-range index (link->type), leading to an out-of-bounds memory access. This can cause undefined behavior such as kernel crashes (denial of service) or potentially memory corruption. The vulnerability stems from insufficient validation of the link->type value before it is used as an array index. The patch introduced adds a validity check for link->type in the bpf_link_show_fdinfo() function and emits a warning if the link type is invalid or if the BPF_LINK_TYPE() macro was missed during the addition of new link types. This fix aims to prevent out-of-bounds access and improve early detection of similar coding errors in the future. The affected versions are identified by a specific commit hash, indicating that the vulnerability exists in certain recent Linux kernel versions prior to the patch. No known exploits are reported in the wild as of the publication date (November 25, 2024), and no CVSS score has been assigned yet. The vulnerability is technical and low-level, affecting the kernel's BPF subsystem, which is widely used for network packet filtering, tracing, and monitoring in Linux environments.

For European organizations, the impact of CVE-2024-53099 depends largely on their use of Linux systems with vulnerable kernel versions, especially those leveraging BPF for network monitoring, security, or performance analysis. Exploitation could lead to kernel crashes causing denial of service, which may disrupt critical services and infrastructure. In more severe cases, out-of-bounds memory access might be leveraged to escalate privileges or execute arbitrary code within the kernel context, although such exploitation would require sophisticated attack techniques and favorable conditions. Organizations running cloud infrastructure, data centers, or embedded Linux devices that utilize BPF are particularly at risk. Disruption of these systems can affect availability and operational continuity. Confidentiality and integrity impacts are less direct but cannot be ruled out if an attacker manages to exploit memory corruption. Given the kernel-level nature, successful exploitation could compromise the entire system. The absence of known exploits currently reduces immediate risk, but the widespread use of Linux in European enterprises and public sector organizations means timely patching is critical to prevent future attacks.

1. Immediate application of the official Linux kernel patch that adds validation for link->type in bpf_link_show_fdinfo() is essential. Monitor Linux kernel mailing lists and vendor advisories for updated kernel releases containing this fix. 2. For organizations using custom or embedded Linux kernels, ensure that the patch is backported and tested before deployment. 3. Implement kernel live patching solutions where feasible to minimize downtime while applying the fix. 4. Restrict access to BPF-related interfaces and capabilities to trusted users and processes only, using Linux security modules (e.g., SELinux, AppArmor) and capability bounding sets to limit potential exploitation vectors. 5. Monitor system logs and kernel warnings for any anomalies related to BPF link types or unexpected warnings emitted by the patched function, which may indicate attempted exploitation or misconfigurations. 6. Conduct internal audits of kernel versions in use across the organization to identify and prioritize vulnerable systems for patching. 7. Employ network segmentation and defense-in-depth strategies to limit the impact of potential kernel-level compromises.