CVE-2024-57893 in Linux
Summary
by MITRE • 01/15/2025
In the Linux kernel, the following vulnerability has been resolved:
ALSA: seq: oss: Fix races at processing SysEx messages
OSS sequencer handles the SysEx messages split in 6 bytes packets, and ALSA sequencer OSS layer tries to combine those. It stores the data in the internal buffer and this access is racy as of now, which may lead to the out-of-bounds access.
As a temporary band-aid fix, introduce a mutex for serializing the process of the SysEx message packets.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 03/09/2026
The vulnerability identified as CVE-2024-57893 resides within the Linux kernel's Advanced Linux Sound Architecture ALSA subsystem, specifically within the OSS (Open Sound System) sequencer layer that handles SysEx (System Exclusive) messages. This issue represents a race condition that occurs during the processing of SysEx messages, which are used in musical instrument digital interface communications to transmit manufacturer-specific data. The vulnerability manifests when the ALSA sequencer's OSS compatibility layer attempts to reconstruct SysEx messages that have been fragmented into 6-byte packets, a common practice in MIDI communication protocols.
The technical flaw stems from improper synchronization mechanisms within the kernel's audio subsystem where multiple threads or processes can simultaneously access the internal buffer used to store and reconstruct SysEx message fragments. This race condition creates a scenario where concurrent access to shared memory resources leads to unpredictable behavior, including potential out-of-bounds memory access patterns that could result in system instability or arbitrary code execution. The vulnerability is classified under CWE-362, which specifically addresses race conditions in concurrent programming environments. The flaw occurs at the kernel level where the OSS sequencer layer attempts to combine fragmented SysEx packets without proper mutual exclusion controls, making it particularly dangerous as it operates within the privileged kernel space.
The operational impact of this vulnerability extends beyond simple system instability, as it could potentially be exploited by malicious actors to achieve privilege escalation or denial of service conditions within audio processing environments. Attackers could craft specially designed SysEx messages that trigger the race condition, leading to memory corruption that might be leveraged for arbitrary code execution with kernel privileges. This presents a significant risk in server environments or systems where audio processing is critical, as the vulnerability could be exploited through legitimate audio input channels. The ATT&CK framework categorizes this under privilege escalation techniques, specifically targeting kernel-level vulnerabilities through race condition exploitation, making it a critical concern for system administrators and security professionals managing Linux-based audio systems.
The mitigation strategy implemented for CVE-2024-57893 involves introducing a mutex lock mechanism to serialize access to the internal buffer used for SysEx message reconstruction. This temporary fix ensures that only one thread can process SysEx message fragments at any given time, eliminating the race condition that previously allowed concurrent access to shared resources. While this approach provides immediate protection against exploitation, it may introduce performance overhead in high-throughput audio environments where multiple SysEx messages are processed simultaneously. The solution aligns with standard kernel security practices for addressing race conditions, though it represents a short-term remediation that may require more comprehensive architectural changes to fully address the underlying synchronization issues in the ALSA subsystem's OSS compatibility layer.