CVE-2024-57893 is a vulnerability identified in the Linux kernel's ALSA (Advanced Linux Sound Architecture) subsystem, specifically within the OSS (Open Sound System) sequencer layer that handles SysEx (System Exclusive) MIDI messages. The vulnerability arises due to a race condition when processing SysEx messages, which are split into 6-byte packets. The OSS sequencer attempts to reassemble these packets by storing them in an internal buffer. However, concurrent access to this buffer is not properly synchronized, leading to a race condition that can cause out-of-bounds memory access. This memory corruption issue could potentially be exploited to cause system instability, crashes, or in some cases, arbitrary code execution depending on the context and privileges of the process handling the messages. The Linux kernel developers have implemented a temporary mitigation by introducing a mutex to serialize access to the buffer during SysEx message processing, reducing the risk of concurrent access and the associated race condition. This fix is a band-aid solution pending a more comprehensive resolution. The vulnerability affects Linux kernel versions identified by the commit hash 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, and no known exploits have been reported in the wild as of the publication date (January 15, 2025). No CVSS score has been assigned yet, and the vulnerability does not require user interaction but does require that the affected ALSA OSS sequencer functionality be in use, which is common in systems handling MIDI audio processing.

For European organizations, the impact of CVE-2024-57893 depends largely on the extent to which Linux systems with ALSA OSS sequencer functionality are deployed, particularly in environments handling audio or MIDI data streams. Organizations in media production, broadcasting, music technology, and embedded systems that rely on Linux for audio processing could face risks of system crashes or potential privilege escalation if attackers exploit this race condition. While no active exploits are known, the out-of-bounds access could be leveraged to destabilize critical systems or gain unauthorized access, impacting confidentiality, integrity, and availability. Systems running Linux kernels with this vulnerability exposed to untrusted MIDI data sources (e.g., networked audio devices or external USB MIDI devices) are at higher risk. The vulnerability could disrupt operations, cause denial of service, or in worst cases, allow attackers to execute arbitrary code, threatening sensitive data and operational continuity. Given the widespread use of Linux in European IT infrastructure, especially in sectors like telecommunications, media, and industrial control, the vulnerability poses a moderate risk that requires timely mitigation to prevent exploitation.

European organizations should prioritize updating their Linux kernels to versions where this vulnerability is patched, ensuring the mutex-based fix or subsequent comprehensive fixes are applied. For systems that cannot be immediately updated, organizations should restrict access to MIDI input sources, especially from untrusted networks or devices, to minimize exposure. Disabling or limiting the use of the OSS sequencer layer in ALSA where feasible can reduce the attack surface. Implementing strict device control policies to prevent unauthorized USB or network MIDI devices from connecting to critical systems is recommended. Monitoring system logs for unusual ALSA or MIDI-related errors or crashes can help detect attempted exploitation. Additionally, organizations should engage with their Linux distribution vendors for backported patches and security advisories. For embedded or specialized Linux systems, vendors should be contacted to ensure timely firmware or kernel updates. Finally, incorporating this vulnerability into vulnerability management and patching workflows will ensure ongoing awareness and remediation.