CVE-2021-47020 is a vulnerability identified in the Linux kernel's SoundWire subsystem, specifically related to the handling of stream configuration errors. SoundWire is an audio interface standard used in embedded and mobile devices to connect audio components. The vulnerability arises from a memory leak occurring when the stream configuration process fails. In the affected code path, the master runtime attempts to release all slave runtimes listed in the slave_rt_list. However, during a configuration failure, the slave runtime is not yet added to this list, resulting in the slave runtime not being freed properly. This leads to a memory leak as the allocated memory for the slave runtime remains unreleased. The patch for this vulnerability modifies the error handling path to explicitly free the slave runtime when the configuration fails, thereby preventing the memory leak. While the vulnerability does not appear to allow direct code execution or privilege escalation, the leak could degrade system performance or stability over time, especially in systems that frequently reconfigure audio streams or run for extended periods without reboot. No known exploits are reported in the wild, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2021-47020 is primarily related to system reliability and resource management rather than direct security breaches. Systems running Linux kernels with the vulnerable SoundWire implementation—commonly found in embedded devices, mobile platforms, and certain industrial or IoT devices—may experience gradual memory exhaustion if audio stream configuration failures occur repeatedly. This could lead to degraded performance, application crashes, or in worst cases, system instability requiring reboots or manual intervention. Organizations relying on Linux-based embedded systems for critical operations (e.g., telecommunications, automotive, industrial control) could face operational disruptions. However, since the vulnerability does not enable remote code execution or privilege escalation, the risk of direct compromise or data breach is low. Nonetheless, persistent memory leaks can be exploited by attackers to cause denial-of-service conditions, which may be leveraged in targeted attacks against critical infrastructure or services.

To mitigate this vulnerability, European organizations should prioritize updating their Linux kernel to the patched version that addresses CVE-2021-47020. This involves applying the official kernel patches or upgrading to a kernel release that includes the fix. For embedded and IoT devices, vendors should be contacted to provide firmware updates incorporating the patch. Additionally, organizations should implement monitoring of system memory usage and logs related to audio subsystem errors to detect abnormal behavior indicative of memory leaks. In environments where immediate patching is not feasible, limiting the frequency of audio stream reconfigurations or disabling SoundWire functionality if not required can reduce exposure. Security teams should also ensure that system recovery procedures are in place to handle potential instability caused by memory exhaustion. Finally, maintaining an inventory of devices using vulnerable Linux kernel versions will help prioritize remediation efforts.