CVE-2025-37938 is a vulnerability identified in the Linux kernel's tracing subsystem, specifically related to the verification of trace event formats that use the "%*p.." format specifier. The Linux kernel includes a trace event verifier that runs at boot or module load time to ensure that trace events do not reference invalid or freed memory. This verifier checks the print formats of trace events and their arguments to confirm that any dereferenced pointers are safe and point only to memory that remains valid when the event is read. The vulnerability arises because the verifier previously ignored trace event formats containing "%*p..", which can lead to unsafe dereferencing of pointers. If an event references data allocated at the time the event was triggered but that data is freed before the event is read, the kernel may attempt to read freed memory, potentially causing a kernel crash (denial of service) or other undefined behavior. The fix involves extending the verifier to cover the "%*p.." format case and adding sample code to demonstrate safe usage of the "%*pbl" format. This vulnerability affects the Linux kernel versions identified by the commit hash 5013f454a352cce8e62162976026a9c472595e42, indicating a specific code state rather than a broad version range. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The vulnerability primarily impacts kernel stability and reliability by enabling potential crashes due to use-after-free conditions in the tracing subsystem.

For European organizations, this vulnerability poses a risk primarily to systems running vulnerable Linux kernel versions, which are widely used in servers, cloud infrastructure, embedded devices, and critical infrastructure components. A successful exploitation could cause kernel crashes leading to denial of service, impacting availability of critical services and systems. This is particularly significant for sectors relying on high availability such as telecommunications, finance, healthcare, and public administration. While there is no indication of remote code execution or privilege escalation, the kernel crash could be triggered by local users or processes that have the ability to generate trace events, potentially including containerized environments or multi-tenant cloud platforms. The impact on confidentiality and integrity is limited, but the availability impact could disrupt business operations and service continuity. Organizations with Linux-based monitoring, tracing, or debugging tools that utilize the affected trace event formats are at higher risk. The absence of known exploits suggests a window for proactive patching before active exploitation occurs.

European organizations should prioritize updating their Linux kernels to versions that include the patch for CVE-2025-37938 as soon as it becomes available. Since the vulnerability relates to the kernel tracing subsystem, administrators should audit and restrict access to tracing interfaces and tools to trusted users only, minimizing the risk of local exploitation. Implementing strict access controls and monitoring usage of tracing features can help detect anomalous activity. For environments using containerization or virtualized Linux instances, ensure that host kernels are patched and that container runtimes do not expose unnecessary tracing capabilities to untrusted containers. Additionally, organizations should review their kernel boot and module loading procedures to confirm that the trace event verifier is active and functioning correctly. Where possible, disable or limit tracing features if they are not required for operational purposes. Maintaining robust system monitoring and alerting for kernel crashes or unusual trace event activity will aid in early detection of exploitation attempts. Finally, coordinate with Linux distribution vendors and subscribe to security advisories to receive timely updates and patches.