CVE-2021-47063 is a use-after-free vulnerability found in the Linux kernel's Direct Rendering Manager (DRM) subsystem, specifically related to the handling of connectors in the bridge/panel driver code. The issue arises because the drm_connector_cleanup() function, which is responsible for properly cleaning up connector objects, is not called manually during the panel_bridge_detach() operation. Instead, the cleanup is deferred to drm_mode_config_cleanup(), which is called later. However, since the drm_connector is allocated using devm (device-managed memory), by the time drm_mode_config_cleanup() is invoked, the connector object has already been freed. This leads to a use-after-free condition where the kernel attempts to access memory that has been released, potentially causing system instability, crashes, or exploitable conditions. The vulnerability was addressed by ensuring that drm_connector_cleanup() is explicitly called when the bridge is detached, preventing the use-after-free scenario. Subsequent patches refined the fix by cleaning up the connector only if it was created and improving the conditional checks to avoid improper cleanup. This vulnerability affects Linux kernel versions containing the specified commit hashes prior to the fix and is relevant to systems using the DRM bridge/panel drivers, which are common in embedded devices, graphical subsystems, and certain hardware configurations relying on Linux for display management. No known exploits are reported in the wild as of the publication date, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2021-47063 depends largely on the deployment of affected Linux kernel versions in their infrastructure. Since the vulnerability is in the DRM subsystem, it primarily affects systems with graphical interfaces or embedded devices using Linux with bridge/panel drivers. This includes workstations, servers with graphical output, embedded systems in industrial control, telecommunications, and IoT devices. Exploitation could lead to kernel crashes (denial of service), potential privilege escalation, or arbitrary code execution if an attacker can trigger the use-after-free condition. This could disrupt critical services, cause downtime, or lead to unauthorized access. Organizations in sectors such as manufacturing, telecommunications, healthcare, and critical infrastructure that rely on Linux-based embedded systems or graphical servers could be particularly vulnerable. The absence of known exploits reduces immediate risk, but the vulnerability's nature suggests that targeted attacks could emerge, especially against high-value targets. The impact on confidentiality, integrity, and availability is significant if exploited, as kernel-level vulnerabilities can compromise the entire system.

European organizations should take the following specific mitigation steps: 1) Identify all Linux systems running kernel versions affected by this vulnerability, focusing on those using DRM bridge/panel drivers. 2) Apply the latest Linux kernel patches that include the fix for CVE-2021-47063 as soon as they are available from trusted sources or distributions. 3) For embedded devices or systems where kernel upgrades are challenging, consider vendor-provided firmware or kernel updates that address this issue. 4) Implement strict access controls and monitoring on systems with graphical interfaces to detect unusual activity that might indicate exploitation attempts. 5) Use kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR), Kernel Page Table Isolation (KPTI), and seccomp filters to reduce the attack surface. 6) Regularly audit and update device drivers and kernel modules to ensure they are not vulnerable. 7) Engage with hardware and software vendors to confirm the status of this vulnerability in their products and request patches if necessary. 8) Maintain robust incident response plans to quickly address potential exploitation attempts.