CVE-2022-49853 is a vulnerability identified in the Linux kernel's macvlan network driver subsystem. The issue arises specifically when the macvlan interface is configured in 'source' mode, which is used to filter traffic based on source MAC addresses. The vulnerability is a memory leak caused by improper cleanup of allocated resources during error handling in the macvlan_common_newlink() function. When the system attempts to add a new macvlan link with source mode enabled, the function macvlan_changelink_sources() is called to reconfigure the list of remote source MAC addresses. If the subsequent call to register_netdevice() fails, the resources allocated by macvlan_changelink_sources() are not released, leading to a memory leak. This leak was detected by kmemleak, a kernel memory leak detector, which reported unreferenced objects remaining allocated after the failure. The patch for this vulnerability ensures that in the event of an error, macvlan_flush_sources() is called to properly free the allocated resources, preventing the leak. While this vulnerability does not directly lead to remote code execution or privilege escalation, the memory leak can degrade system stability and performance over time, especially on systems that frequently create and destroy macvlan interfaces in source mode. The vulnerability affects Linux kernel versions prior to the patch commit identified by the hash aa5fd0fb77486b8a6764ead8627baa14790e4280. No known exploits are reported in the wild as of the publication date, and no CVSS score has been assigned.

For European organizations, the impact of CVE-2022-49853 primarily concerns system reliability and resource management on Linux-based infrastructure that utilizes macvlan interfaces in source mode. Enterprises running containerized environments, virtualized network functions, or complex network segmentation relying on macvlan may experience gradual memory exhaustion if the vulnerability is exploited or triggered repeatedly. This can lead to degraded network performance, potential service interruptions, or system crashes, impacting availability. Although the vulnerability does not directly compromise confidentiality or integrity, the resulting denial of service conditions could disrupt critical services, especially in sectors with high dependency on Linux servers such as finance, telecommunications, and public administration. Given the widespread use of Linux in European data centers and cloud environments, unpatched systems could face operational risks. However, the absence of known exploits and the requirement for specific macvlan source mode configuration somewhat limit the immediate threat scope.

European organizations should prioritize updating their Linux kernels to versions that include the patch identified by commit aa5fd0fb77486b8a6764ead8627baa14790e4280 or later. System administrators should audit their network configurations to identify usage of macvlan interfaces, particularly those configured in source mode. Where possible, avoid or limit the use of macvlan source mode until patches are applied. Implement monitoring for unusual memory usage patterns on network hosts to detect potential leaks early. Incorporate kernel memory leak detection tools such as kmemleak in testing and staging environments to proactively identify similar issues. For environments where immediate patching is not feasible, consider isolating affected systems or limiting the frequency of macvlan interface creation and deletion to reduce leak impact. Regularly review Linux kernel security advisories and subscribe to vendor update channels to ensure timely application of security patches.