Introduction
Privilege escalation in multi-tenant cloud and confidential computing environments can undermine trusted execution itself. CVE-2025-26403 affects Intel Xeon 6 processors running SGX or TDX, two technologies widely used to protect sensitive workloads in enterprise and cloud data centers.
Intel is the world's largest x86 processor manufacturer, and its Xeon processors are a core platform for cloud, enterprise, and high-performance computing. Intel SGX and TDX are hardware-based trusted execution technologies designed to isolate sensitive code and data, even from privileged system software. Hyperscale cloud providers, financial institutions, and other organizations with strict confidentiality requirements use them.
Technical information
CVE-2025-26403 is an out-of-bounds write vulnerability (CWE-787) in the memory subsystem of Intel Xeon 6 processors. The flaw is present only when Intel SGX (Software Guard Extensions) or TDX (Trust Domain Extensions) is enabled and in use. Its root cause is insufficient bounds checking during memory operations tied to these trusted execution environments.
A local privileged user who triggers the flaw can write data beyond the intended boundaries of allocated memory buffers. That can corrupt critical data structures in the memory subsystem and may lead to escalation of privilege. The vulnerability is not exploitable remotely and requires local access with elevated privileges. No public code snippets or proof of concept are available.
The flaw sits in the hardware logic or microcode that implements SGX and TDX. Xeon 6 processors with SGX and TDX disabled or not in use are not affected.
Affected systems and versions
- Intel Xeon 6 processors
- Only systems with Intel SGX or TDX enabled and actively used are vulnerable
- Public sources give no further version granularity
Vendor security history
Intel has a well-documented history of vulnerabilities in its trusted execution and memory isolation technologies, including Spectre, Meltdown, and multiple flaws in its SGX and TDX implementations. Intel typically coordinates with OEMs to release microcode and firmware updates, and it publishes security advisories through the Intel Security Center. The company has improved its disclosure and patching processes since 2018, but hardware-based security features remain complex and difficult to get right.
