CVE-2022-48651 is a high-severity vulnerability in the Linux kernel's ipvlan network driver, specifically related to the handling of the mac_header field in socket buffers (skb) when using AF_PACKET sockets with the PACKET_QDISC_BYPASS option. The issue arises because when an AF_PACKET socket is configured to send packets through ipvlan and the transmit function is changed from dev_queue_xmit() to packet_direct_xmit() via setsockopt(), the skb->mac_header field may not be properly reset. Instead, it retains an invalid initial value of 65535. This leads to an out-of-bounds memory access when the ipvlan_xmit_mode_l2() function attempts to access the MAC header using eth_hdr(), which calculates the header pointer as skb->head + skb->mac_header. Since skb->mac_header is invalid, this results in a slab-out-of-bounds bug, potentially causing kernel memory corruption or crashes. The root cause is twofold: first, packet_snd() only resets skb->mac_header when the socket type is SOCK_RAW and the protocol is unspecified, which is not the case here; second, packet_direct_xmit() does not reset skb->mac_header, unlike dev_queue_xmit(). The vulnerability was fixed by replacing eth_hdr() with skb_eth_hdr() in ipvlan_xmit_mode_l2(), which safely handles the MAC header, and by resetting the mac_header in multicast scenarios to prevent out-of-bounds access. This vulnerability is classified under CWE-125 (Out-of-bounds Read) and has a CVSS 3.1 base score of 7.7, indicating high severity. It requires local access (AV:L), low attack complexity (AC:L), no privileges (PR:N), and no user interaction (UI:N). The impact affects integrity and availability but not confidentiality. No known exploits are reported in the wild as of the published date. The affected versions include specific Linux kernel commits prior to the patch. This vulnerability is particularly relevant for environments using ipvlan interfaces with AF_PACKET sockets configured with PACKET_QDISC_BYPASS, which may be common in advanced networking setups, containerized environments, or virtualized infrastructure relying on Linux kernel networking features.

For European organizations, the impact of CVE-2022-48651 can be significant in environments where Linux servers are used with ipvlan networking, especially in data centers, cloud providers, and enterprises leveraging container orchestration platforms like Kubernetes that may use ipvlan for network virtualization. The out-of-bounds memory access can lead to kernel crashes (denial of service) or potentially allow an attacker to corrupt kernel memory, impacting system integrity and availability. Although the vulnerability does not directly expose confidentiality breaches, the resulting instability can disrupt critical services. Given the prevalence of Linux in European IT infrastructure, including government, finance, telecommunications, and manufacturing sectors, exploitation could cause service outages or require emergency patching, impacting business continuity. The requirement for local access limits remote exploitation but insider threats or compromised internal hosts could leverage this vulnerability to escalate attacks or disrupt operations. Additionally, virtualized and containerized environments common in European cloud deployments may be particularly exposed if they use the affected ipvlan configurations.

1. Apply the official Linux kernel patches that address CVE-2022-48651 as soon as possible. Ensure that all Linux systems, especially those running kernel versions prior to the fix, are updated. 2. Audit network configurations to identify use of ipvlan interfaces combined with AF_PACKET sockets using PACKET_QDISC_BYPASS. Where possible, avoid or restrict the use of PACKET_QDISC_BYPASS to trusted applications. 3. Implement strict access controls and monitoring on systems that allow local socket operations to limit potential exploitation by unprivileged users. 4. Use kernel hardening features such as Kernel Address Sanitizer (KASAN) in testing environments to detect similar memory corruption issues early. 5. For containerized environments, ensure container runtimes and orchestration platforms are updated and configured to minimize exposure to vulnerable kernel features. 6. Monitor system logs and kernel crash reports for signs of exploitation attempts or instability related to ipvlan networking. 7. Employ network segmentation and least privilege principles to reduce the risk of local attackers gaining access to vulnerable systems.