CVE-2025-38240 is a vulnerability identified in the Linux kernel specifically within the Direct Rendering Manager (DRM) subsystem for MediaTek DisplayPort (dp) driver code. The issue arises from improper handling of error logging in the HPD (Hot Plug Detect) path. The function mtk_dp_wait_hpd_asserted() can be invoked before the pointer mtk_dp->drm_dev is properly assigned during the bridge attachment process (mtk_dp_bridge_attach()). This leads to a NULL pointer dereference when drm-level error logging (drm_err) is used, as drm_err attempts to access the uninitialized drm_dev pointer. The vulnerability is triggered through a call chain involving mtk_edp_wait_hpd_asserted, panel probe, and dp_aux_ep_probe functions. The fix involves replacing drm_err calls with dev_err calls in mtk_dp_wait_hpd_asserted() and mtk_dp_parse_capabilities(), which do not dereference the drm_dev pointer, thus preventing the NULL pointer dereference. Additionally, error codes were added to the messages to aid debugging. This vulnerability is a classic NULL pointer dereference leading to a potential kernel crash (denial of service) but does not appear to allow privilege escalation or arbitrary code execution. No known exploits are reported in the wild. The affected versions correspond to specific Linux kernel commits identified by hash, indicating this is a recent and targeted fix in the kernel source code. No CVSS score has been assigned yet.

For European organizations, the primary impact of CVE-2025-38240 is the potential for denial of service (DoS) on Linux systems running the affected kernel versions with MediaTek DisplayPort drivers. This could cause system instability or crashes when the vulnerable code path is exercised, potentially disrupting services relying on graphical output or display management. While the vulnerability does not directly lead to data breaches or privilege escalation, the resulting DoS could affect critical infrastructure, industrial control systems, or enterprise environments using Linux-based systems with MediaTek hardware. Organizations in sectors such as telecommunications, manufacturing, and embedded systems where MediaTek chipsets are common could face operational interruptions. The lack of known exploits reduces immediate risk, but the vulnerability could be leveraged in targeted attacks or combined with other exploits. The impact on confidentiality and integrity is minimal; the main concern is availability degradation.

To mitigate this vulnerability, European organizations should: 1) Identify Linux systems running kernels with MediaTek DisplayPort drivers, especially those using affected commit versions or close derivatives. 2) Apply the official Linux kernel patches that replace drm_err with dev_err in the affected functions as soon as they are available in stable kernel releases or backported patches. 3) If patching is not immediately feasible, consider disabling or limiting the use of MediaTek DisplayPort functionality temporarily to avoid triggering the vulnerable code path. 4) Monitor system logs for crashes or error messages related to mtk_dp_wait_hpd_asserted or related DRM components to detect potential exploitation attempts or instability. 5) Implement robust kernel crash recovery and system monitoring to minimize downtime in case of DoS. 6) Engage with Linux distribution vendors for timely updates and advisories. 7) For embedded or specialized devices, coordinate with hardware vendors for firmware or driver updates addressing this issue.