CVE-2024-25744 is a high-severity vulnerability affecting the Linux kernel versions prior to 6.6.7. The flaw resides in the handling of the int80 syscall interface within the kernel, specifically related to the code paths in arch/x86/coco/tdx/tdx.c and arch/x86/mm/mem_encrypt_amd.c. This vulnerability allows an untrusted Virtual Machine Monitor (VMM) to trigger the int80 syscall handling at arbitrary points during execution. The int80 interface is a legacy mechanism used by user-space applications to invoke system calls on x86 architectures. Improper handling of this interface by the kernel can lead to serious security implications. The vulnerability is linked to CWE-693, which involves protection mechanism failures, indicating that the kernel's safeguards against improper syscall invocation are insufficient. The CVSS v3.1 base score is 8.8, reflecting a high impact on confidentiality, integrity, and availability, with an attack vector requiring local access but low complexity and low privileges. The scope is changed, meaning the vulnerability can affect components beyond the initially vulnerable module. No known exploits are currently reported in the wild, and no vendor patches or product-specific details are provided in the source information. The vulnerability is particularly relevant to environments using AMD memory encryption technologies and Intel TDX (Trusted Domain Extensions), as indicated by the affected source files. These technologies are used to enhance security in virtualized environments, but the flaw allows an untrusted VMM to manipulate syscall handling, potentially leading to privilege escalation, data leakage, or denial of service.

For European organizations, this vulnerability poses significant risks, especially for those relying on Linux-based virtualized infrastructure using AMD SEV (Secure Encrypted Virtualization) or Intel TDX technologies. Exploitation could allow malicious or compromised VMMs to escalate privileges within guest virtual machines, bypassing isolation guarantees and potentially accessing sensitive data or disrupting critical services. This is particularly concerning for sectors such as finance, healthcare, telecommunications, and government, where virtualization is heavily used for workload consolidation and cloud services. The high impact on confidentiality, integrity, and availability means that successful exploitation could lead to data breaches, unauthorized control over systems, and service outages. Given the widespread use of Linux in European data centers and cloud providers, the vulnerability could affect a broad range of organizations, including managed service providers and enterprises running private clouds. The lack of known exploits currently reduces immediate risk but does not diminish the urgency for mitigation, as attackers may develop exploits rapidly once the vulnerability is public.

European organizations should prioritize updating Linux kernels to version 6.6.7 or later, where the vulnerability is addressed. In environments where immediate patching is not feasible, organizations should restrict the ability of untrusted or less-trusted VMMs to manage or interact with guest VMs, enforcing strict access controls and monitoring for unusual syscall activity. Employing kernel hardening techniques such as seccomp filters to restrict syscall usage and leveraging virtualization security features that limit VMM privileges can reduce attack surface. Additionally, organizations should audit their virtualization infrastructure to identify use of AMD SEV and Intel TDX technologies and apply vendor-specific guidance for secure configuration. Monitoring and logging of syscall invocations and hypervisor behavior can help detect exploitation attempts. Collaboration with cloud service providers to ensure patched environments and secure hypervisor configurations is also recommended. Finally, organizations should prepare incident response plans for potential exploitation scenarios involving virtualization escape or privilege escalation.