CVE-2024-42154 is a vulnerability identified in the Linux kernel's TCP metrics subsystem. Specifically, the issue arises from insufficient validation of the source address length for the attribute TCP_METRICS_ATTR_SADDR_IPV4. The vulnerability stems from the absence of a check ensuring that the IPv4 source address attribute is at least 4 bytes long, which is the expected size for an IPv4 address. Additionally, the policy governing attribute validation lacks an entry for this IPv4 attribute, unlike the IPv6 counterpart, which undergoes manual validation. This flaw could potentially allow malformed or truncated source address data to be processed by the kernel's TCP metrics functionality. While the exact exploitation method is not detailed, improper validation of network packet attributes in kernel space can lead to memory corruption, denial of service (DoS), or potentially privilege escalation if exploited by an attacker sending crafted TCP packets. The vulnerability affects multiple versions of the Linux kernel, as indicated by the repeated commit hash references, suggesting a widespread presence in kernel builds prior to the patch. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The issue was reserved and published in late July 2024, indicating recent discovery and remediation efforts. The patch presumably involves adding proper length validation checks for the TCP_METRICS_ATTR_SADDR_IPV4 attribute to prevent processing of malformed data.

For European organizations, the impact of CVE-2024-42154 depends largely on their reliance on Linux-based systems, particularly those running kernel versions affected by this vulnerability. Linux is widely used across European enterprises, government agencies, and critical infrastructure sectors such as telecommunications, finance, energy, and public services. A successful exploitation could lead to kernel crashes causing denial of service, disrupting critical services and operations. In worst-case scenarios, if the vulnerability enables privilege escalation, attackers could gain unauthorized control over affected systems, leading to data breaches, lateral movement within networks, and potential sabotage. Given the kernel-level nature of the flaw, the confidentiality, integrity, and availability of systems could be severely impacted. However, the lack of known exploits and the technical complexity of crafting suitable malformed packets may limit immediate risk. Still, organizations with exposed Linux servers, especially those handling sensitive or critical workloads, should consider this vulnerability a significant threat that requires prompt attention to prevent potential exploitation.

European organizations should prioritize applying the official Linux kernel patches that address CVE-2024-42154 as soon as they become available from their Linux distribution vendors. In environments where immediate patching is not feasible, network-level mitigations can be employed, such as filtering or rate-limiting suspicious TCP traffic that could carry malformed TCP metrics attributes. Intrusion detection and prevention systems (IDS/IPS) should be updated to recognize anomalous TCP metrics packets. System administrators should audit their Linux kernel versions and confirm whether they are running affected builds, especially in critical infrastructure and production environments. Additionally, organizations should implement strict network segmentation and limit exposure of Linux servers to untrusted networks to reduce attack surface. Monitoring kernel logs for unusual TCP metrics-related errors or crashes can help detect attempted exploitation. Finally, maintaining robust incident response plans and backups will aid in recovery if exploitation occurs.