CVE-2021-47604 is a vulnerability identified in the Linux kernel specifically related to the vduse (vhost-user device emulation) component. The issue arises in the get_config() function where an offset parameter is not properly validated against the device's configuration size (dev->config_size). While the length (len) parameter is checked to ensure it is within bounds, the offset is not similarly verified. Since both offset and dev->config_size are unsigned integers, if offset exceeds dev->config_size, the subtraction dev->config_size - offset results in a large unsigned value due to underflow. This can lead to an out-of-bounds read operation, potentially exposing kernel memory contents or causing undefined behavior. The vulnerability stems from insufficient input validation, although it is noted that the parameters are expected to have been validated earlier by the vhost_vdpa_config_validate() function. However, this assumption may not hold in all code paths, making the additional check necessary for safety. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The vulnerability affects specific Linux kernel versions identified by commit hashes, indicating it is present in certain kernel builds prior to patching. The vulnerability is a memory safety issue that could be leveraged by a local attacker or a malicious virtualized environment component to read sensitive kernel memory or cause instability in the kernel's vduse subsystem.

For European organizations, the impact of CVE-2021-47604 depends on their use of Linux systems that employ the vduse/vhost-user device emulation functionality, commonly found in virtualization and container environments. Organizations running virtualized infrastructure, cloud services, or edge computing platforms on Linux kernels with this vulnerability may face risks of information disclosure or kernel instability. An attacker with access to the affected subsystem could exploit the out-of-bounds read to leak sensitive kernel memory, potentially exposing cryptographic keys, credentials, or other confidential data. This could compromise confidentiality and integrity of systems. Additionally, kernel instability could lead to denial of service conditions affecting availability. Given the widespread use of Linux in European data centers, cloud providers, and critical infrastructure, the vulnerability could have significant operational and security implications if exploited. However, the lack of known exploits and the requirement for specific kernel configurations and local access reduce the immediate threat level. Nonetheless, organizations in sectors such as finance, telecommunications, government, and critical infrastructure should be particularly vigilant due to the strategic importance of their systems and the prevalence of Linux virtualization technologies.

European organizations should take the following specific mitigation steps: 1) Identify Linux systems running kernel versions affected by CVE-2021-47604, focusing on those utilizing vduse or vhost-user device emulation features. 2) Apply the official Linux kernel patches or upgrade to a kernel version where this vulnerability is resolved. Since no patch links are provided, organizations should monitor the official Linux kernel mailing lists and repositories for the relevant fixes. 3) Review and harden virtualization configurations to limit untrusted code execution within virtualized environments, reducing the risk of local exploitation. 4) Implement strict access controls and monitoring on systems hosting virtualized workloads to detect anomalous behavior indicative of exploitation attempts. 5) Conduct code audits or use static analysis tools to verify that input validation functions like vhost_vdpa_config_validate() are correctly applied in custom or backported kernel builds. 6) Employ kernel security modules (e.g., SELinux, AppArmor) to restrict the capabilities of processes interacting with the vduse subsystem. 7) Maintain up-to-date intrusion detection and prevention systems capable of identifying suspicious kernel-level activities. These steps go beyond generic advice by focusing on the specific subsystem and operational context of the vulnerability.