CVE-2024-50085 is a high-severity vulnerability affecting the Linux kernel's implementation of Multipath TCP (MPTCP), specifically within the path manager netlink interface. The flaw is a use-after-free (UaF) condition occurring in the function mptcp_pm_nl_rm_addr_or_subflow, which is responsible for removing addresses or subflows in the MPTCP path manager netlink code. This vulnerability was discovered and reported by the Syzkaller fuzzing tool, which triggered a kernel crash (splat) due to a slab-use-after-free error detected by Kernel Address Sanitizer (KASAN). The detailed kernel stack trace shows that the issue arises when the kernel attempts to read memory that has already been freed, leading to undefined behavior, potential kernel crashes, or arbitrary code execution in kernel context. MPTCP is an extension of TCP that allows multiple paths to be used simultaneously between two endpoints, improving redundancy and throughput. The vulnerability lies in the netlink interface used for managing MPTCP addresses and subflows, which is accessible to processes with certain privileges. The CVSS v3.1 score is 7.8 (high), reflecting that the attack vector is local (AV:L), requires low complexity (AC:L), privileges (PR:L), no user interaction (UI:N), and impacts confidentiality, integrity, and availability (C:H/I:H/A:H). Exploiting this flaw could allow a local attacker with limited privileges to cause a denial of service via kernel crashes or potentially escalate privileges by executing arbitrary code in kernel space. The vulnerability affects multiple Linux kernel versions, including recent mainline releases, as indicated by the affected commit hashes. No public exploits are known at this time, but the presence of a use-after-free in kernel networking code is a serious concern given the potential for privilege escalation and system compromise. The patch details are not included in the provided information, but Linux kernel maintainers have resolved the issue in recent updates. This vulnerability is categorized under CWE-416 (Use After Free), a common and dangerous class of memory corruption bugs. The technical details confirm the vulnerability is published and enriched by CISA, highlighting its significance in the cybersecurity community.

For European organizations, the impact of CVE-2024-50085 can be substantial, especially for those relying on Linux-based infrastructure, servers, and network appliances that utilize MPTCP. Since MPTCP is used to enhance network reliability and performance, particularly in data centers, cloud environments, and telecom infrastructure, exploitation could lead to kernel crashes causing service outages (availability impact). Furthermore, successful exploitation could allow local attackers to escalate privileges, potentially compromising the confidentiality and integrity of sensitive data and systems. Organizations in sectors such as finance, telecommunications, government, and critical infrastructure that deploy Linux servers or network devices with MPTCP enabled are at higher risk. The vulnerability could be leveraged by malicious insiders or attackers who have gained limited access to systems to deepen their foothold or disrupt operations. Given the high CVSS score and the kernel-level impact, the threat could lead to significant operational disruption, data breaches, or lateral movement within networks. The lack of known exploits in the wild currently reduces immediate risk, but the vulnerability's nature and severity warrant prompt attention. European organizations with compliance obligations under GDPR and other regulations must consider the potential data protection implications of a kernel-level compromise. Additionally, the widespread use of Linux in European research institutions, cloud providers, and enterprises increases the attack surface.

1. Immediate patching: Organizations should prioritize updating their Linux kernels to the latest versions where this vulnerability is fixed. Kernel updates from trusted Linux distributions (Debian, Ubuntu, Red Hat, SUSE, etc.) should be applied promptly. 2. Disable MPTCP if not required: If MPTCP functionality is not essential, disable it to reduce the attack surface. This can be done by disabling the MPTCP kernel module or configuring the kernel to not load MPTCP support. 3. Restrict local access: Since the vulnerability requires local privileges, tighten access controls to limit who can execute code or commands on Linux hosts. Use strong authentication, role-based access control, and monitoring to detect unauthorized access. 4. Kernel hardening: Employ kernel hardening techniques such as Kernel Address Sanitizer (KASAN) in testing environments to detect similar issues early. Use security modules like SELinux or AppArmor to confine processes and reduce impact. 5. Monitor and audit: Implement monitoring for unusual kernel crashes or system instability that could indicate exploitation attempts. Audit logs for suspicious local activity around netlink communications related to MPTCP. 6. Vendor coordination: Coordinate with Linux distribution vendors and hardware providers to ensure timely receipt and deployment of patches. Subscribe to security advisories for rapid awareness. 7. Incident response readiness: Prepare incident response plans for potential kernel-level compromises, including forensic capabilities to analyze kernel dumps and memory. These steps go beyond generic advice by focusing on disabling unused features, restricting local access, and leveraging kernel hardening and monitoring specific to this vulnerability's characteristics.