CVE-2023-52842 is a vulnerability identified in the Linux kernel's virtio_vsock subsystem, specifically within the virtio_transport_recv_pkt() function. The issue arises from uninitialized values in the virtio_vsock header structure, namely the buf_alloc and fwd_cnt fields, which are not properly initialized when a new socket buffer (skb) is allocated in virtio_transport_init_hdr(). This leads to the use of uninitialized memory during packet reception processing. The vulnerability was detected by Kernel Memory Sanitizer (KMSAN), which flagged an uninitialized value access in the kernel's virtio transport code path. The virtio_vsock interface is used to facilitate communication between virtual machines and the host or between virtual machines themselves, commonly in virtualized environments such as those using QEMU/KVM. The flaw could potentially lead to undefined behavior, including information leakage or kernel memory corruption, depending on how the uninitialized data is used. The vulnerability is triggered by creating and connecting a VSOCK socket, as demonstrated by the provided simple reproducer code snippet. The root cause is the failure to initialize certain fields in the virtio_vsock header structure during skb allocation, which was fixed by initializing these fields properly in the patch. This vulnerability affects Linux kernel versions containing the specified commits prior to the fix and is relevant to systems running virtualized workloads that utilize the virtio_vsock interface. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2023-52842 primarily concerns environments that rely heavily on Linux-based virtualized infrastructure, including cloud providers, data centers, and enterprises using virtualization technologies such as KVM/QEMU. The vulnerability could allow an attacker with the ability to create or manipulate VSOCK connections to cause kernel memory corruption or leak sensitive kernel memory contents, potentially leading to privilege escalation or denial of service conditions. This is particularly critical for organizations running multi-tenant virtualized environments where isolation between virtual machines is paramount. Confidentiality could be compromised if uninitialized kernel memory contains sensitive data, and integrity could be affected if memory corruption leads to unpredictable kernel behavior. Availability might also be impacted if the kernel crashes or deadlocks due to the flaw. Although exploitation requires the ability to create VSOCK connections, which typically implies some level of access to the host or guest VM, the risk remains significant in environments where virtual machine isolation is critical. European organizations in sectors such as finance, telecommunications, and government, which often use Linux virtualization extensively, could face operational disruptions or data breaches if this vulnerability is exploited.

To mitigate this vulnerability, European organizations should promptly apply the Linux kernel patches that initialize the buf_alloc and fwd_cnt fields in the virtio_vsock header structure during skb allocation. This requires updating to a Linux kernel version that includes the fix for CVE-2023-52842. Organizations should prioritize patching virtualized hosts and guest systems that use the virtio_vsock interface. Additionally, restricting access to VSOCK interfaces to trusted users and processes can reduce the attack surface. Implementing strict access controls and monitoring for unusual VSOCK socket creation or connection attempts can help detect potential exploitation attempts. For environments where immediate patching is not feasible, consider disabling or limiting the use of virtio_vsock interfaces if they are not essential. Regular kernel security updates and vulnerability scanning should be part of the operational security posture to ensure timely detection and remediation of such issues. Finally, organizations should conduct thorough testing of virtualized workloads after patching to ensure stability and security.