CVE-2021-47587 is a vulnerability identified in the Linux kernel's network subsystem, specifically related to the SYSTEMPORT hardware interface and its handling of transmit (TX) queues. The root cause lies in the lack of a global locking mechanism for the lifecycle of descriptors shared across multiple transmit queues. Currently, the locking only protects concurrency within individual transmit queues, but when multiple transmit queues operate concurrently, the SYSTEMPORT hardware may process corrupted descriptors. This leads to inconsistencies such as UDP and TCP packets having correct checksum calculations over incorrect packet lengths, indicating data corruption at the descriptor level. The SYSTEMPORT hardware maintains an internal descriptor list that it rearranges when the driver writes to the WRITE_PORT_HI and WRITE_PORT_LO registers. Due to hardware reorganization delays, concurrent writes from multiple TX queues can break the internal allocation scheme, causing the length and status fields of descriptors to reference incorrect data buffers. The vulnerability can result in corrupted network packets being transmitted, potentially causing network communication errors or data integrity issues. The fix implemented involves introducing a global serialization lock across all TX queues during the critical section where the WRITE_PORT_HI and WRITE_PORT_LO registers are written. This serialization prevents concurrent access and thus eliminates descriptor corruption even when multiple TX queues are active simultaneously. No known exploits are reported in the wild, and no CVSS score has been assigned yet. The vulnerability affects Linux kernel versions identified by the provided commit hash, indicating it is relevant to specific kernel builds incorporating SYSTEMPORT hardware support.

For European organizations, this vulnerability poses risks primarily to network reliability and data integrity in environments using Linux systems with SYSTEMPORT hardware and multiple transmit queues enabled. Corrupted packet descriptors can lead to malformed network packets, which may cause application-level errors, degraded network performance, or intermittent communication failures. In critical infrastructure sectors such as telecommunications, finance, and government services where Linux-based network appliances or servers are common, this could disrupt operations or degrade service quality. Although the vulnerability does not directly enable remote code execution or privilege escalation, the resulting network anomalies could be exploited as part of a broader attack chain or cause denial of service conditions. Additionally, organizations relying on high-throughput or multi-queue network configurations may be more exposed. The absence of known exploits reduces immediate risk, but unpatched systems remain vulnerable to potential future exploitation or operational issues. Given the widespread use of Linux in European data centers, cloud providers, and enterprise environments, the impact could be significant if not addressed promptly.

European organizations should prioritize updating their Linux kernel to versions that include the patch introducing global serialization for TX queue descriptor writes. Specifically, kernel maintainers and system administrators should track and apply the patch referenced by the commit hash 80105befdb4b8cea924711b40b2462b87df65b62 or later stable releases containing this fix. Network administrators should audit systems using SYSTEMPORT hardware and multiple transmit queues to identify vulnerable hosts. Temporary mitigation could include disabling multiple transmit queues if feasible, reducing concurrency to avoid triggering the descriptor corruption, though this may impact network performance. Monitoring network traffic for anomalies such as checksum mismatches or malformed packets can help detect exploitation or manifestation of the issue. Coordination with hardware vendors to confirm compatibility with patched kernel versions is advised. Finally, incorporating this vulnerability into vulnerability management and patching cycles ensures timely remediation.