CVE-2025-37966 is a vulnerability identified in the Linux kernel specifically affecting the RISC-V architecture implementation. The issue arises when a userspace process attempts to use the PR_SET_TAGGED_ADDR_CTRL prctl operation while the Supm (Supervisor User-Mode Memory Protection) extension is not available on the system. This results in the kernel executing an illegal instruction, causing a kernel crash (Oops) and leading to a denial of service condition. The root cause is the kernel's failure to verify the presence of the Supm extension before executing the set_tagged_addr_ctrl function, which manipulates tagged address control registers. The crash occurs due to an illegal instruction triggered by the absence of the required hardware extension, as evidenced by the kernel stack trace and error codes provided. The vulnerability has been addressed by adding a check for the availability of the Supm extension before performing the operation, preventing the kernel from crashing under these conditions. This vulnerability is specific to the RISC-V architecture within Linux and does not affect other architectures. No known exploits are reported in the wild at the time of publication, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2025-37966 primarily involves potential denial of service on Linux systems running on RISC-V processors without the Supm extension. While RISC-V adoption in Europe is currently limited compared to x86 and ARM architectures, it is growing in embedded systems, IoT devices, and specialized computing environments. Organizations using RISC-V Linux systems could experience unexpected kernel crashes triggered by malicious or malformed userspace requests, leading to service interruptions or system instability. This could affect critical infrastructure or industrial control systems if they employ RISC-V Linux platforms. However, since exploitation requires userspace code to invoke the specific prctl operation, the attack surface is limited to local or privileged users who can execute such code. There is no indication that remote exploitation is possible without prior access. The absence of known exploits reduces immediate risk, but the vulnerability could be leveraged in targeted attacks or privilege escalation scenarios. Overall, the threat is moderate for European organizations with RISC-V Linux deployments, with the main risk being availability disruption.

To mitigate CVE-2025-37966, European organizations should: 1) Apply the latest Linux kernel updates that include the patch checking for the Supm extension before executing PR_SET_TAGGED_ADDR_CTRL operations. 2) Audit and restrict access to systems running RISC-V Linux kernels, limiting userspace execution privileges to trusted users and processes to reduce the risk of malicious prctl calls. 3) Monitor kernel logs for Oops or illegal instruction errors related to set_tagged_addr_ctrl to detect potential exploitation attempts or misconfigurations. 4) For embedded or IoT devices using RISC-V Linux, ensure firmware and kernel versions are updated and consider disabling or restricting prctl operations if not required. 5) Implement system integrity monitoring and incident response plans tailored to RISC-V Linux environments to quickly respond to any denial of service or instability events. These steps go beyond generic advice by focusing on architecture-specific controls, privilege management, and proactive monitoring.