CVE-2025-26403 is a vulnerability identified in certain Intel Xeon 6 processors when operating with Intel Software Guard Extensions (SGX) or Intel Trust Domain Extensions (TDX). The flaw is an out-of-bounds write within the processor's memory subsystem, which can be triggered by a privileged local user. This memory corruption could potentially allow the attacker to escalate their privileges beyond what is normally permitted. Intel SGX and TDX are technologies designed to create isolated execution environments (enclaves or trusted domains) to protect sensitive computations and data from unauthorized access, even from privileged system software. The vulnerability undermines these protections by enabling a local attacker with high privileges to write outside intended memory boundaries, potentially compromising the confidentiality and integrity of enclave or trusted domain data. The CVSS 4.5 score reflects that the attack requires local access and high privileges, with high complexity and scope limited to the affected system. No user interaction is required, and no known exploits have been reported in the wild as of the publication date. The affected versions are not explicitly listed but pertain to Intel Xeon 6 processors supporting SGX or TDX. The vulnerability was reserved in March 2025 and published in August 2025. Intel is expected to release microcode and firmware patches to address this issue. Until patches are applied, systems remain vulnerable if an attacker gains privileged local access.

For European organizations, the impact of CVE-2025-26403 can be significant in environments relying on Intel SGX or TDX for secure computation, such as financial institutions, cloud service providers, and government agencies. The vulnerability allows a privileged local attacker to escalate privileges, potentially leading to unauthorized access to sensitive enclave data, manipulation of secure computations, or disruption of trusted execution environments. This could result in data breaches, loss of data integrity, and service disruptions. Since SGX and TDX are often used to protect highly sensitive workloads, exploitation could undermine trust in secure computing platforms and lead to regulatory compliance issues under GDPR and other data protection laws. However, the requirement for high privilege and local access limits the attack surface primarily to insiders or attackers who have already compromised a system to some extent. The absence of known exploits reduces immediate risk but does not eliminate the threat. Organizations with large-scale deployments of Intel Xeon 6 processors in critical infrastructure or cloud environments are particularly at risk.

1. Apply Intel microcode and firmware updates as soon as they become available to remediate the vulnerability at the hardware level. 2. Restrict and monitor privileged local access to systems running Intel Xeon 6 processors with SGX or TDX enabled, employing strict access controls and least privilege principles. 3. Implement robust endpoint detection and response (EDR) solutions to detect anomalous local activities indicative of privilege escalation attempts. 4. Conduct regular security audits and vulnerability assessments focusing on systems utilizing SGX and TDX technologies. 5. Consider disabling SGX or TDX features temporarily if they are not essential to operations until patches are applied. 6. Employ hardware-based attestation and integrity verification mechanisms to detect unauthorized changes to trusted execution environments. 7. Educate system administrators and security teams about the specific risks associated with this vulnerability to improve incident response readiness.