Introduction
Privilege escalation in multi-tenant cloud and confidential computing environments can undermine the very foundation of trusted execution. CVE-2025-26403 directly impacts Intel Xeon 6 processors running SGX or TDX, two technologies widely adopted to secure sensitive workloads in enterprise and cloud data centers.
About the involved parties: Intel is the largest x86 processor manufacturer globally, with Xeon processors forming the backbone of 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. Their adoption spans hyperscale cloud providers, financial institutions, and organizations with stringent confidentiality requirements.
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 only present when either Intel SGX (Software Guard Extensions) or TDX (Trust Domain Extensions) is enabled and in use. The vulnerability is rooted in insufficient bounds checking during memory operations associated with these trusted execution environments.
When triggered, a local privileged user can write data beyond the intended boundaries of allocated memory buffers. This can corrupt critical data structures within the memory subsystem, potentially leading 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 for this issue.
The vulnerability is specific to the hardware logic or microcode that implements SGX and TDX features. It does not affect Xeon 6 processors where SGX and TDX are disabled or not in use.
Affected Systems and Versions
- Intel Xeon 6 processors
- Only systems with Intel SGX or TDX enabled and actively used are vulnerable
- No further version granularity is available in public sources
Vendor Security History
Intel has a well-documented history of vulnerabilities in its trusted execution and memory isolation technologies. Notable examples include Spectre, Meltdown, and multiple flaws in SGX and TDX implementations. Intel typically coordinates with OEMs to release microcode and firmware updates, and its security advisories are published through the Intel Security Center. The company has improved its disclosure and patching processes since 2018, but the complexity of hardware-based security features continues to present challenges.