CVE-2021-47297 is a medium-severity vulnerability in the Linux kernel affecting the CAIF (Cellular Interface) network protocol implementation, specifically in the caif_seqpkt_sendmsg function. The issue arises due to the use of uninitialized stack memory when the number of segments (nr_segs) is zero in the iovec_from_user function. This leads to the msg->msg_iter.iov pointer being uninitialized, which is then dereferenced without proper validation in caif_seqpkt_sendmsg. The vulnerability is rooted in improper handling of message buffers during the sendmsg system call, potentially causing undefined behavior or kernel crashes. The kernel's Kernel Memory Sanitizer (KMSAN) detected this uninitialized value usage, indicating a memory safety flaw. Exploitation requires local privileges (PR:L), no user interaction (UI:N), and has a low attack complexity (AC:L). The impact is limited to availability (A:H), meaning an attacker with some privileges could cause a denial of service by crashing the kernel or causing instability, but confidentiality and integrity are not affected. The vulnerability does not appear to have known exploits in the wild as of the publication date. The affected versions correspond to specific Linux kernel commits identified by their hashes, indicating this is a recent fix. The vulnerability is relevant for systems using the CAIF protocol, which is primarily used in embedded or cellular communication contexts within Linux environments.

For European organizations, the primary impact of CVE-2021-47297 is the potential for denial-of-service (DoS) conditions on Linux systems utilizing the CAIF protocol stack. This could affect embedded devices, network equipment, or cellular communication infrastructure running vulnerable Linux kernels. Organizations in telecommunications, critical infrastructure, and industries relying on embedded Linux devices may experience service disruptions or system instability. Since the vulnerability requires local privileges, the risk is higher in environments where untrusted users have some level of access or where privilege escalation chains exist. The lack of impact on confidentiality and integrity reduces the risk of data breaches but does not eliminate operational risks. European telecom providers and industrial control systems using Linux-based cellular interfaces could be particularly sensitive to this vulnerability, as service availability is critical. Additionally, any disruption in embedded systems within manufacturing or transportation sectors could have cascading effects on operational continuity.

To mitigate CVE-2021-47297, European organizations should: 1) Apply the latest Linux kernel patches that address this vulnerability as soon as they become available, ensuring that the CAIF protocol implementation is updated. 2) Audit and restrict local user privileges to minimize the risk of exploitation by unprivileged users. 3) Implement strict access controls and monitoring on systems running embedded or cellular Linux stacks to detect abnormal behavior or crashes related to sendmsg system calls. 4) For embedded devices, coordinate with vendors to obtain firmware updates incorporating the patched kernel versions. 5) Employ kernel hardening techniques such as Kernel Address Sanitizer (KASAN) and Kernel Memory Sanitizer (KMSAN) during development and testing phases to detect similar issues proactively. 6) Conduct regular security assessments of embedded Linux systems, focusing on network protocol stacks and local privilege boundaries. 7) Consider network segmentation to isolate vulnerable devices and limit the impact of potential DoS conditions.