CVE-2021-47519 is a high-severity vulnerability identified in the Linux kernel's CAN (Controller Area Network) subsystem, specifically within the m_can_read_fifo() function. The issue is a memory leak caused by improper error handling. When the second call to m_can_fifo_read() fails, the function jumps to an error handling label (out_fail) and returns without freeing the socket buffer (skb) that was previously allocated by alloc_can_skb(). This results in the allocated memory not being released, leading to a memory leak. The vulnerability was discovered through static analysis using GCC's -fanalyzer feature. The patch for this vulnerability introduces a goto label to ensure that the skb is properly destroyed if an error occurs, thus preventing the memory leak. The vulnerability is categorized under CWE-401 (Improper Release of Memory Before Removing Last Reference) and has a CVSS v3.1 base score of 7.5, indicating a high severity. The CVSS vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) shows that the vulnerability is remotely exploitable over the network without requiring privileges or user interaction, and it impacts availability by causing resource exhaustion through memory leakage. No known exploits are currently reported in the wild. The affected versions correspond to specific Linux kernel commits identified by their hashes, implying that this issue affects certain kernel versions prior to the patch. This vulnerability is particularly relevant for systems utilizing the CAN protocol, which is commonly used in automotive, industrial control, and embedded systems running Linux.

For European organizations, the impact of CVE-2021-47519 can be significant in environments where Linux-based systems implement CAN bus communication, such as automotive manufacturers, industrial automation companies, and embedded device vendors. The memory leak can lead to gradual resource exhaustion, causing system instability, crashes, or denial of service (DoS). In critical infrastructure sectors like manufacturing, transportation, and energy, such disruptions could affect operational continuity and safety. Although the vulnerability does not directly compromise confidentiality or integrity, the availability impact can indirectly affect business operations and safety-critical functions. European automotive companies, which are leaders in CAN bus technology integration, may face increased risk if their Linux-based embedded systems are unpatched. Additionally, industrial control systems in European factories that rely on Linux CAN drivers could experience degraded performance or outages. Given the remote exploitability without authentication or user interaction, attackers could potentially trigger the memory leak remotely, increasing the threat surface. However, the absence of known exploits in the wild suggests that immediate widespread attacks are unlikely but patching remains critical to prevent future exploitation.

To mitigate CVE-2021-47519, European organizations should prioritize updating their Linux kernel to the patched versions that address this memory leak. Specifically, system administrators should: 1) Identify all Linux systems utilizing the CAN subsystem, particularly those running affected kernel versions identified by the commit hashes. 2) Apply the official Linux kernel patches that fix the m_can_read_fifo() memory leak or upgrade to a kernel version that includes the fix. 3) For embedded or specialized devices where kernel upgrades are challenging, coordinate with device vendors to obtain firmware updates or mitigations. 4) Implement monitoring for unusual memory consumption patterns on CAN-related processes or kernel modules to detect potential exploitation attempts. 5) Employ network segmentation to isolate CAN-enabled devices from untrusted networks, reducing exposure to remote attacks. 6) Conduct regular vulnerability assessments and penetration testing focused on embedded and industrial Linux systems to ensure no residual vulnerabilities remain. These steps go beyond generic advice by focusing on the specific subsystem and operational context of the vulnerability.