CVE-2025-21998 is a vulnerability identified in the Linux kernel, specifically within the firmware component related to Qualcomm's UEFI Secure Application (uefisecapp). The issue arises from a race condition during the initialization of the efivars service, which manages EFI variables. The vulnerability is rooted in the transition to using the Trusted Zone (TZ) allocator for memory management. In this process, the efivars service is registered before the memory pool required for its operation has been allocated. This premature registration can lead to a NULL-pointer dereference if there is concurrent access to EFI variables, causing a race condition. A NULL-pointer dereference typically results in a kernel crash or system instability, potentially leading to a denial of service (DoS). The fix involves ensuring that all necessary resources, including the memory pool, are fully allocated and initialized before the efivars service is registered, thereby eliminating the race condition. Although no known exploits are currently reported in the wild, the vulnerability affects the Linux kernel versions identified by the given commit hashes, which are likely part of recent or development branches. The absence of a CVSS score indicates that the vulnerability is newly disclosed and has not yet been fully assessed for severity.

For European organizations, this vulnerability poses a risk primarily in environments running Linux kernels with the affected Qualcomm UEFI firmware components, which are common in embedded systems, servers, and potentially some desktop environments. The primary impact is the potential for denial of service through kernel crashes caused by the NULL-pointer dereference. This can disrupt critical services, especially in infrastructure relying on Linux-based systems for networking, cloud services, or embedded applications. While the vulnerability does not directly enable privilege escalation or data breach, the resulting system instability could be exploited as part of a broader attack chain or cause significant operational downtime. Organizations in sectors such as telecommunications, manufacturing, and cloud service providers, which often use Qualcomm-based hardware or Linux kernels with UEFI support, may face increased risk. The lack of known exploits reduces immediate threat but does not eliminate the risk of future exploitation once the vulnerability details become widely known.

European organizations should prioritize updating their Linux kernels to versions where this vulnerability has been patched, ensuring that the efivars service registration occurs only after all memory pools and resources are fully initialized. For systems where immediate patching is not feasible, organizations should implement strict access controls to EFI variables and limit untrusted user or process interactions that could trigger the race condition. Monitoring system logs for kernel crashes or unusual EFI variable access patterns can help detect attempted exploitation. Additionally, organizations should review their firmware update processes to ensure Qualcomm UEFI components are up to date. For embedded and IoT devices using affected kernels, coordinated firmware updates and vendor communication are essential. Finally, incorporating this vulnerability into vulnerability management and incident response plans will help prepare for potential exploitation attempts.