CVE-2024-35841 is a vulnerability identified in the Linux kernel's networking subsystem, specifically within the TLS (Transport Layer Security) sendmsg implementation that handles splicing of user-provided pages into kernel scatterlists for transmission. The vulnerability arises in the code path that processes MSG_SPLICE_PAGES flags during TLS sendmsg operations. When a user attempts to splice more pages into the message than the maximum allowed scatterlist fragments (MAX_MSG_FRAGS), the code incorrectly aborts the scatterlist setup without properly marking the message as a 'full record'. This leads to a logic flaw where the sendmsg code attempts to continue sending data into an already full scatterlist, triggering warnings and potentially causing unexpected behavior. The root cause is that the MORE flag, which hints the kernel to delay sending until more data is available, is not overridden when the scatterlist is full, resulting in a fallthrough to a continuation path that mishandles the message state. The fix involves ensuring that if the scatterlist is full (full_record not set), the message is sent immediately regardless of the MORE flag, preventing the erroneous continuation and associated warnings. This vulnerability is a logic error in kernel TLS message handling that could cause instability or denial of service conditions due to improper message state management during high-volume or crafted TLS splicing operations. No known exploits are reported in the wild as of the publication date, and the vulnerability affects specific Linux kernel versions identified by commit hashes. The issue is technical and relates to internal kernel memory and message buffer management during TLS sendmsg operations, which are critical for secure network communication in Linux environments.

For European organizations, the impact of CVE-2024-35841 primarily concerns systems running affected Linux kernel versions with TLS offloading enabled in the networking stack. Since Linux is widely deployed across servers, cloud infrastructure, and embedded devices in Europe, this vulnerability could lead to service disruptions or denial of service (DoS) conditions if exploited by sending specially crafted TLS splice messages that trigger the faulty logic. Although no direct remote code execution or privilege escalation is indicated, the instability caused by the kernel warnings and aborted message processing could degrade the availability of critical network services, including web servers, VPN gateways, and other TLS-dependent applications. Organizations relying on Linux-based infrastructure for secure communications may face increased risk of network outages or degraded performance, impacting business continuity and service reliability. Additionally, the vulnerability could be leveraged as part of a multi-stage attack to cause resource exhaustion or kernel panics, especially in high-throughput environments. Given the importance of Linux in European data centers, telecommunications, and government systems, timely patching is essential to maintain operational stability and security compliance.

To mitigate CVE-2024-35841, European organizations should: 1) Identify and inventory Linux systems running affected kernel versions, particularly those using TLS offloading or advanced networking features involving MSG_SPLICE_PAGES. 2) Apply the official Linux kernel patches or updates that address this vulnerability as soon as they become available from trusted sources or Linux distribution vendors. 3) In environments where immediate patching is not feasible, consider disabling TLS offloading or the use of MSG_SPLICE_PAGES in the kernel networking stack as a temporary workaround to prevent triggering the vulnerable code path. 4) Monitor kernel logs and system alerts for warnings related to __sk_msg_free or TLS sendmsg operations that may indicate attempts to exploit this issue. 5) Conduct network traffic analysis to detect abnormal TLS splicing patterns that could signal exploitation attempts. 6) Maintain strict access controls and network segmentation to limit exposure of vulnerable systems to untrusted networks or users. 7) Engage with Linux distribution security advisories and maintain an up-to-date patch management process to quickly respond to emerging threats related to this vulnerability.