CVE-2021-47526 is a vulnerability identified in the Linux kernel's serial liteuart driver. The issue arises due to improper handling of the driver data pointer (drvdata) during the device removal process. Specifically, if drvdata is not set during the probe phase (_probe()), the subsequent call to platform_get_drvdata() in the remove function (_remove()) results in a NULL pointer dereference. This causes a kernel BUG, leading to a system crash or kernel panic. The vulnerability is rooted in a logic error where the driver fails to initialize the necessary data structures before device removal, causing the kernel to dereference a NULL pointer. Although this is a denial-of-service (DoS) type vulnerability rather than a remote code execution flaw, it can cause system instability or downtime. The vulnerability affects Linux kernel versions identified by the commit hash 1da81e5562fac8286567422cc56a7fbd0dc646d4, and it has been publicly disclosed as of May 24, 2024. There are no known exploits in the wild at this time, and no CVSS score has been assigned. The fix involves ensuring drvdata is properly set in the probe function to prevent the NULL pointer dereference during removal.

For European organizations, the primary impact of CVE-2021-47526 is the potential for denial-of-service conditions on Linux systems using the affected liteuart serial driver. This could lead to unexpected system crashes or kernel panics, resulting in service interruptions, especially in environments where Linux is used for critical infrastructure or embedded systems relying on serial communication. While the vulnerability does not allow for privilege escalation or data compromise directly, the resulting downtime could disrupt operations, cause loss of availability, and impact business continuity. Organizations running Linux kernels with this vulnerable driver, particularly in industrial control systems, telecommunications, or embedded device contexts, may experience operational instability. The lack of known exploits reduces immediate risk, but unpatched systems remain vulnerable to accidental or malicious triggering of the bug.

To mitigate CVE-2021-47526, organizations should: 1) Apply the official Linux kernel patches that ensure drvdata is properly initialized in the liteuart driver's probe function. 2) Update Linux kernel versions to the latest stable releases that include this fix. 3) Audit systems to identify usage of the liteuart serial driver, especially in embedded or specialized hardware environments. 4) Implement monitoring for kernel panics or crashes related to serial device removal events to detect potential exploitation attempts or accidental triggers. 5) For critical systems, consider isolating or limiting access to devices using the liteuart driver until patched. 6) Incorporate this vulnerability into vulnerability management and patching schedules to ensure timely remediation. 7) Test patches in staging environments to verify stability before deployment in production.