CVE-2024-50261 is a high-severity use-after-free (UAF) vulnerability in the Linux kernel's MACsec (Media Access Control Security) implementation. MACsec is a security protocol that provides data confidentiality, integrity, and origin authenticity for Ethernet frames. The vulnerability arises from improper memory management of the metadata_dst structure, which stores the Secure Channel Identifier (SCI) used for MACsec offloading. Specifically, the metadata_dst is prematurely freed by metadata_dst_free() in macsec_free_netdev(), but the driver continues to reference it when sending packets. This leads to a use-after-free condition detected by Kernel Address Sanitizer (KASAN) during packet transmission in the mlx5_core driver (mlx5e_xmit function). The flaw allows an attacker with limited privileges (requires local privileges and no user interaction) to potentially execute arbitrary code, cause denial of service (kernel panic or system crash), or escalate privileges by exploiting the dangling pointer. The fix involves replacing the immediate free call with dst_release(), which defers freeing until all references are released, preventing premature deallocation. The vulnerability affects Linux kernel versions identified by the commit hash 0a28bfd4971fd570d1f3e4653b21415becefc92c and likely other versions containing the vulnerable MACsec code. The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity but requiring local privileges. No known exploits are currently reported in the wild, but the vulnerability's nature and kernel component affected make it a significant risk for systems using MACsec offloading, especially on hardware using mlx5 (Mellanox) drivers.

For European organizations, the impact of CVE-2024-50261 can be substantial, particularly for enterprises and service providers relying on Linux-based infrastructure with MACsec enabled for secure Ethernet communications. MACsec is often deployed in data centers, telecom networks, and critical infrastructure to protect data in transit at Layer 2. Exploitation could allow attackers to compromise system integrity, gain elevated privileges, or cause denial of service, disrupting network security and availability. This is especially critical for sectors such as finance, telecommunications, government, and energy, where secure and reliable network operations are paramount. The vulnerability could also undermine compliance with European data protection regulations (e.g., GDPR) if confidentiality is breached. Since the flaw requires local privileges, insider threats or compromised user accounts pose a risk vector. The absence of known exploits provides a window for proactive patching, but the high severity score necessitates urgent attention to prevent potential targeted attacks.

1. Immediate application of the official Linux kernel patches that address CVE-2024-50261 is essential. Organizations should track kernel updates from their Linux distribution vendors and deploy security updates promptly. 2. Disable MACsec offloading on network interfaces using mlx5 drivers if patching cannot be immediately applied, as a temporary mitigation to prevent triggering the vulnerability. 3. Restrict local user privileges and enforce strict access controls to minimize the risk of local exploitation. 4. Monitor system logs and kernel messages for unusual activity or KASAN reports indicating use-after-free errors related to MACsec or mlx5e_xmit. 5. Conduct thorough audits of network device configurations to ensure MACsec is correctly implemented and unnecessary offloading features are disabled. 6. Employ host-based intrusion detection systems (HIDS) to detect anomalous kernel behavior. 7. For critical environments, consider network segmentation to limit exposure of vulnerable systems. 8. Educate system administrators about this vulnerability and the importance of timely patch management in kernel components.