CVE-2022-49672 is a vulnerability identified in the Linux kernel's network subsystem, specifically related to the TUN (network tunnel) device driver. The issue arises from a race condition between the destruction of the tun file and the associated network device. In the Linux kernel, NAPI (New API) structures are used to improve network packet processing efficiency by enabling interrupt mitigation and polling mechanisms. These NAPI instances are embedded within the tun_file structure. The vulnerability occurs because the current kernel code does not explicitly delete the NAPI if the network queue was detached first, leading to a scenario where the tun_file structure (and its NAPI) can be destroyed before the network device itself. This improper cleanup can cause use-after-free conditions or dangling pointers, potentially leading to kernel crashes or undefined behavior. The root cause is a missing explicit deletion of the NAPI during device destruction, which Syzbot—a kernel fuzzing tool—discovered. The vulnerability affects multiple versions of the Linux kernel as indicated by the repeated affected version hashes, though exact version numbers are not specified. There are no known exploits in the wild at the time of publication, and no CVSS score has been assigned yet. The vulnerability was published on February 26, 2025, and is currently in a published state without an official patch link provided in the data. This vulnerability is technical and low-level, affecting the core Linux kernel networking stack, which is widely used in servers, embedded devices, and cloud infrastructure.

For European organizations, the impact of CVE-2022-49672 could be significant, especially for those relying heavily on Linux-based infrastructure for networking, virtualization, and containerization. The TUN device is commonly used for VPNs, virtual networking in cloud environments, and container networking. Exploitation of this race condition could lead to kernel crashes (denial of service), potential privilege escalation, or arbitrary code execution if an attacker can manipulate the timing of device destruction and NAPI deletion. This could disrupt critical services, including secure communications and cloud workloads. Organizations in sectors such as finance, telecommunications, government, and critical infrastructure, which often use Linux extensively, could face operational disruptions and increased risk of targeted attacks. Although no exploits are known currently, the vulnerability’s nature suggests that skilled attackers with local access or the ability to trigger network device teardown could exploit it. This risk is heightened in multi-tenant environments like cloud providers or shared hosting, common in Europe. Additionally, the lack of a patch at the time of publication means organizations must be vigilant in monitoring for updates and may need to implement temporary mitigations.

1. Immediate application of kernel updates once patches become available from Linux distributions is critical. Monitor official Linux kernel mailing lists and vendor advisories for patch releases addressing this vulnerability. 2. Until patches are available, limit access to systems running vulnerable kernel versions to trusted users only, minimizing the risk of local exploitation. 3. Restrict or monitor usage of TUN devices, especially in multi-tenant or shared environments, to reduce attack surface. 4. Employ kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR), Kernel Page Table Isolation (KPTI), and seccomp filters to reduce the impact of potential exploitation. 5. Use security monitoring tools to detect unusual kernel crashes or suspicious activity related to network device teardown. 6. For cloud providers and virtualized environments, consider isolating workloads that require TUN devices to dedicated hosts or containers with strict resource and access controls. 7. Engage with Linux distribution vendors to prioritize backporting patches for affected kernel versions commonly deployed in European organizations. 8. Conduct internal audits to identify systems running affected kernel versions and plan for timely remediation.