CVE-2021-47135 is a vulnerability identified in the Linux kernel, specifically within the mt76 wireless driver component for the mt7921 chipset. The issue involves a possible array out-of-bounds (AOOB) access in the function mt7921_mcu_tx_rate_report. This function handles transmission rate reporting for the mt7921 wireless device. An out-of-bounds access can lead to memory corruption, which may cause system instability, crashes, or potentially enable an attacker to execute arbitrary code or escalate privileges if exploited. The vulnerability was addressed by fixing the array boundary checks and removing unnecessary variables to prevent such memory access errors. Although no known exploits are currently reported in the wild, the presence of this vulnerability in the Linux kernel, which is widely used across many distributions and devices, makes it a significant concern. The affected versions are identified by specific commit hashes, indicating that the vulnerability exists in certain kernel builds prior to the patch. The vulnerability does not have an assigned CVSS score yet, but it has been published and enriched by CISA, highlighting its importance. The mt7921 chipset is commonly found in modern wireless networking hardware, meaning that devices using this driver could be vulnerable if running unpatched kernel versions.

For European organizations, the impact of CVE-2021-47135 could be substantial due to the widespread use of Linux-based systems in enterprise environments, including servers, desktops, and embedded devices. The vulnerability affects wireless networking components, which are critical for connectivity in corporate networks. Exploitation could lead to denial of service through system crashes or potentially unauthorized code execution, compromising confidentiality, integrity, and availability of systems. This is particularly concerning for organizations relying on Linux for critical infrastructure, cloud services, or IoT deployments. The absence of known exploits reduces immediate risk, but the potential for future exploitation remains. Disruption of wireless communications could affect operational continuity, especially in sectors like finance, manufacturing, and public services that depend on reliable network access. Additionally, compromised devices could serve as entry points for lateral movement within networks, increasing the risk of broader compromise.

Organizations should promptly apply the patches provided by Linux kernel maintainers that address this vulnerability. Since the affected versions are identified by specific commit hashes, ensuring that systems are updated to kernel versions including the fix is critical. Network administrators should audit their Linux systems to identify those using the mt76 driver with the mt7921 chipset and verify patch status. Employing kernel live patching solutions can reduce downtime during updates. Additionally, implementing strict network segmentation and monitoring wireless traffic for anomalies can help detect exploitation attempts. Disabling or restricting the use of vulnerable wireless hardware where feasible can reduce exposure. Regular vulnerability scanning and maintaining an up-to-date asset inventory will aid in managing risk. Finally, organizations should stay informed about any emerging exploit reports or additional patches related to this vulnerability.