CVE-2025-37803 is a vulnerability identified in the Linux kernel, specifically within the udmabuf subsystem. The issue relates to a buffer size overflow that occurs during the creation of a udmabuf buffer. The root cause is an incorrect calculation of the page limit (pglimit) due to improper casting of the size_limit_mb variable. By casting size_limit_mb to a 64-bit unsigned integer (u64), the overflow condition is mitigated. Without this fix, the buffer size calculation could overflow, potentially leading to memory corruption. This could allow an attacker with the ability to create udmabuf buffers to trigger undefined behavior, which might include privilege escalation, denial of service, or arbitrary code execution depending on the context and kernel configuration. The vulnerability affects multiple versions of the Linux kernel, as indicated by the repeated commit hash references, suggesting a widespread issue in the affected kernel releases. There are no known exploits in the wild at the time of publication, and no CVSS score has been assigned yet. The vulnerability was reserved in mid-April 2025 and published in early May 2025. The udmabuf subsystem is used for user-space DMA buffer allocation, commonly leveraged in embedded systems, multimedia applications, and other performance-sensitive environments where direct memory access is required. The lack of a CVSS score and limited technical details restrict a full assessment, but the nature of the overflow in kernel space indicates a potentially serious security flaw.

For European organizations, the impact of CVE-2025-37803 could be significant, especially for those relying on Linux-based infrastructure in critical environments such as telecommunications, industrial control systems, cloud services, and embedded devices. Exploitation of this vulnerability could lead to kernel memory corruption, resulting in system crashes (denial of service) or privilege escalation, allowing attackers to gain unauthorized root access. This could compromise confidentiality, integrity, and availability of systems and data. Organizations running custom or older Linux kernels that include the vulnerable udmabuf implementation are at risk. Given the widespread use of Linux across European enterprises, including government, finance, and manufacturing sectors, the vulnerability could be leveraged to disrupt operations or facilitate lateral movement within networks. However, the absence of known exploits and the requirement for the attacker to have the ability to create udmabuf buffers somewhat limits the attack surface to privileged or semi-privileged users or processes. Nonetheless, in environments where untrusted users have some level of access, or where containerized workloads share kernel resources, the risk increases.

To mitigate CVE-2025-37803, European organizations should prioritize updating their Linux kernels to versions that include the patch fixing the udmabuf buffer size overflow. Since the fix involves proper casting to prevent overflow, applying the official kernel updates from trusted sources is critical. Organizations should audit their systems to identify usage of the udmabuf subsystem, particularly in embedded devices, multimedia servers, or systems handling DMA buffers. Restricting access to udmabuf creation interfaces to trusted users and processes can reduce exploitation risk. Employing kernel security modules (e.g., SELinux, AppArmor) to enforce strict access controls on device files related to udmabuf is recommended. Additionally, monitoring kernel logs and system behavior for anomalies related to memory corruption or crashes can provide early detection. For environments using containerization or virtualization, ensuring proper isolation and limiting container privileges can help prevent exploitation. Finally, organizations should maintain an inventory of Linux kernel versions deployed across their infrastructure and establish rapid patch management processes to respond to such vulnerabilities promptly.