CVE-2022-48757 is a vulnerability identified in the Linux kernel related to information leakage through the /proc/net/ptype interface. The issue arises when a packet socket is created within one network namespace but is not bound to a specific device. In this scenario, users in other network namespaces can observe the new packet_type entry created by this socket by reading the /proc/net/ptype file. This behavior leads to minor information leakage across network namespaces. The vulnerability stems from the fact that the packet_type entries do not properly associate the packet socket with its originating network namespace, allowing cross-namespace visibility. The fix involves adding a net pointer to each packet_type entry to track the corresponding network namespace and modifying the ptype_seq_show function to verify this pointer before exposing information. This ensures that packet_type entries are only visible within their respective network namespaces, preventing unauthorized information disclosure. Although the vulnerability is considered minor due to the namespace awareness of packet sockets, it still violates the isolation principles of Linux network namespaces and could potentially be used as an information-gathering vector by attackers or malicious users sharing the same host environment. The vulnerability affects Linux kernel versions identified by the commit hash 2feb27dbe00cbb4f7d31f90acf6bd0d751dd0a50 and was published on June 20, 2024. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2022-48757 is relatively low but should not be dismissed. The vulnerability allows minor information leakage between network namespaces on Linux systems, which could be exploited in multi-tenant environments such as cloud infrastructure, containerized deployments, or virtualized hosting platforms where network namespaces are heavily used to isolate tenants or applications. Unauthorized users might glean information about packet socket configurations or network namespace activities, potentially aiding in reconnaissance or lateral movement within a compromised system. However, this vulnerability does not directly allow privilege escalation, code execution, or denial of service. Confidentiality is impacted to a limited extent due to information leakage, but integrity and availability remain unaffected. European organizations that rely extensively on Linux-based servers, especially those running container orchestration platforms like Kubernetes or using network namespaces for security segmentation, should consider this vulnerability in their threat models. The risk is higher in environments where multiple untrusted users share the same host or where strict namespace isolation is critical for compliance or security policies.

To mitigate CVE-2022-48757, organizations should apply the Linux kernel patch that adds namespace awareness to the packet_type entries as soon as it becomes available from their Linux distribution vendors. Specifically, ensure that the kernel version includes the fix that adds the net pointer to packet_type and the corresponding checks in ptype_seq_show. For environments using custom or older kernels, backporting the patch may be necessary. Additionally, organizations should audit their use of network namespaces and packet sockets to minimize unnecessary exposure. Restricting access to /proc/net/ptype and related procfs interfaces through mandatory access controls (e.g., SELinux, AppArmor) or by limiting user privileges can reduce the risk of information leakage. Monitoring for unusual access patterns to /proc/net/ptype and implementing strict user separation policies on multi-tenant systems will further reduce potential exploitation. Finally, maintain up-to-date Linux kernel versions and subscribe to vendor security advisories to promptly address similar namespace isolation vulnerabilities.