CVE-2024-47728 is a vulnerability identified and resolved in the Linux kernel related to the Berkeley Packet Filter (BPF) subsystem, specifically concerning argument handling in BPF helper functions. The issue arises from improper zeroing of former ARG_PTR_TO_{LONG,INT} arguments in non-tracing BPF helpers when an error occurs. Without zeroing these arguments, there is a risk of leaking kernel memory contents, which could expose sensitive information. The vulnerability does not affect tracing helpers because they require CAP_PERFMON capability, which already allows reading kernel memory, and thus the functions bpf_get_func_arg() and bpf_get_func_ret() are skipped in that context. Additionally, the vulnerability involves the handling of MTU (Maximum Transmission Unit) helper functions where the mtu_len pointer value is both read and written. The Linux kernel's verifier currently uses a MEM_UNINIT flag that implies memory writes without the need for initialization, but lifting this flag would require significant rework because it would change the semantics to require initialized memory for reads. The current fix involves clearing the mtu_len pointer on error paths to prevent uninitialized memory reads and potential memory corruption or leakage. This vulnerability is subtle and relates to the internal memory management and verification logic of BPF programs, which are widely used for network packet filtering, tracing, and performance monitoring. Exploitation could lead to information disclosure of kernel memory, potentially aiding attackers in further privilege escalation or kernel exploitation. No known exploits are reported in the wild as of the publication date.

For European organizations, this vulnerability poses a risk primarily to systems running vulnerable Linux kernel versions that support BPF functionality. Since BPF is extensively used in modern Linux distributions for networking, security monitoring, and performance tracing, the impact could be significant in environments relying on Linux servers, cloud infrastructure, and network appliances. Information leakage of kernel memory could allow attackers to bypass security controls or gain insights into kernel internals, facilitating more advanced attacks such as privilege escalation or targeted kernel exploits. Organizations in sectors with high reliance on Linux-based infrastructure, such as telecommunications, cloud service providers, financial institutions, and critical infrastructure operators, could face increased risk. The vulnerability does not require user interaction but does require the ability to load or execute BPF programs, which may be restricted in hardened environments. However, in less restricted or misconfigured systems, attackers could exploit this flaw to gain sensitive information. The absence of known exploits suggests that immediate widespread impact is limited, but the potential for future exploitation remains, especially as BPF usage grows.

European organizations should prioritize updating their Linux kernel to the patched versions that address CVE-2024-47728 as soon as possible. Kernel updates from trusted distributors should be applied promptly. Additionally, organizations should audit and restrict the ability to load and execute BPF programs to trusted users and processes only, leveraging Linux security modules (e.g., SELinux, AppArmor) and capabilities management to limit CAP_BPF and CAP_PERFMON privileges. Network and system administrators should monitor for unusual BPF program loading activities and implement runtime security tools that can detect anomalous kernel memory access patterns. For environments where immediate patching is not feasible, consider disabling or limiting BPF functionality if it is not essential. Regularly review kernel configurations and security policies to ensure minimal exposure to kernel-level vulnerabilities. Finally, maintain comprehensive logging and incident response capabilities to detect and respond to potential exploitation attempts.