CVE-2021-47432 is a medium-severity vulnerability identified in the Linux kernel, specifically within the generic radix tree implementation found in the file lib/generic-radix-tree.c. The issue arises from an integer overflow in the peek() function of the radix tree code, triggered by the expansion of inode numbers into a larger 64-bit inode space. This overflow can cause incorrect behavior or kernel crashes (kernel oops), impacting system availability. The radix tree is a fundamental data structure used extensively in the Linux kernel for efficient storage and retrieval of data indexed by integers, including inode management. An integer overflow in this context can lead to memory corruption or unexpected kernel faults. The vulnerability requires local privileges with low complexity to exploit (AV:L/AC:L/PR:L/UI:N), meaning an attacker with some level of access to the system but not full administrative rights could potentially trigger the issue without user interaction. The CVSS v3.1 base score is 5.5, reflecting a medium severity primarily due to its impact on availability (A:H) without affecting confidentiality or integrity. No known exploits are currently reported in the wild, and no patches or exploit code links are provided in the data. The vulnerability was published recently on May 21, 2024, and has been enriched by CISA, indicating recognition by US cybersecurity authorities. Given the nature of the bug, it could cause system instability or denial of service conditions if exploited, but it does not appear to allow privilege escalation or data compromise directly.

For European organizations, the primary impact of CVE-2021-47432 lies in potential system availability disruptions. Linux is widely deployed across European enterprises, government agencies, and critical infrastructure, often powering servers, cloud environments, and embedded systems. A successful exploitation could cause kernel crashes leading to downtime or service interruptions, which may affect business continuity, especially in sectors relying on high availability such as finance, telecommunications, and public services. Although the vulnerability does not compromise confidentiality or integrity, denial of service conditions can still have significant operational and reputational consequences. Organizations running Linux kernels with affected versions, particularly those with multi-user environments or shared hosting, are at risk if attackers with limited privileges can trigger the overflow. The absence of known exploits reduces immediate risk, but the vulnerability’s presence in a core kernel component means that targeted attacks or accidental triggering during normal operations remain concerns. Additionally, embedded Linux devices used in industrial control systems or IoT deployments in Europe could be impacted, potentially affecting critical infrastructure stability.

To mitigate CVE-2021-47432, European organizations should prioritize updating their Linux kernel to versions where this vulnerability is patched. Since no direct patch links are provided, organizations should monitor official Linux kernel repositories and distributions for updates addressing this radix tree overflow. System administrators should audit their environments to identify affected kernel versions and plan timely upgrades. Given the local access requirement, organizations should also enforce strict access controls and minimize the number of users with privileges sufficient to exploit this flaw. Implementing kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR) and enabling security modules like SELinux or AppArmor can reduce exploitation likelihood. Regular system integrity monitoring and kernel crash logging should be enabled to detect abnormal behavior indicative of exploitation attempts. For embedded or IoT devices running Linux, vendors and operators should coordinate to ensure firmware updates are applied promptly. Finally, organizations should incorporate this vulnerability into their risk management and incident response plans to prepare for potential denial of service scenarios.