CVE-2025-31356 Overview
CVE-2025-31356 affects Intel Trust Domain Extensions (Intel TDX) within Ring 0 hypervisor operations. The flaw stems from insufficient verification of data authenticity [CWE-345], which can allow information disclosure to a privileged local adversary. Intel TDX is designed to isolate virtual machines (trust domains) from the host hypervisor and other software, protecting confidential workloads on Intel Xeon processors. This weakness undermines that isolation guarantee under specific conditions requiring high attack complexity and privileged access. Intel disclosed the issue in security advisory SA-01419.
Critical Impact
A local, privileged system-software adversary can leverage this weakness to expose confidential data protected by Intel TDX trust domains, weakening the confidentiality guarantees the technology is intended to enforce.
Affected Products
- Intel Trust Domain Extensions (Intel TDX)
- Intel Xeon processors implementing Intel TDX Ring 0 hypervisor components
- Systems relying on Intel TDX for confidential virtual machine isolation
Discovery Timeline
- 2026-08-11 - CVE-2025-31356 published to NVD
- 2026-08-12 - Last updated in NVD database
Technical Details for CVE-2025-31356
Vulnerability Analysis
Intel TDX establishes hardware-enforced trust domains that isolate guest virtual machines from an untrusted hypervisor. The technology relies on cryptographic and structural verification of data crossing trust boundaries to prevent tampering and leakage. This vulnerability arises because certain data handled by TDX components within Ring 0 hypervisor code is not sufficiently verified for authenticity before use.
When authenticity checks are incomplete, a system software adversary operating with high privileges can craft or influence inputs that pass through TDX processing paths without triggering rejection. The result is exposure of confidential information that should remain protected inside a trust domain. Exploitation requires local access, high privileges, and specific attack conditions that raise complexity, but no user interaction. The primary impact is loss of confidentiality, with a limited integrity impact and no availability effect.
Root Cause
The root cause is classified as insufficient verification of data authenticity [CWE-345] within Intel TDX Ring 0 hypervisor components. Missing or weakened validation steps allow adversary-controlled data to be processed as trusted, defeating boundary enforcement between the hypervisor and trust domains.
Attack Vector
The attack vector is local. An adversary must already control privileged system software on the host, such as a compromised hypervisor or malicious platform component, and must satisfy additional attack requirements that increase complexity. Under those conditions, the adversary can trigger the flawed verification path to extract confidential data from TDX-protected memory or metadata. No user interaction is required.
Refer to the Intel Security Advisory SA-01419 for authoritative technical details.
Detection Methods for CVE-2025-31356
Indicators of Compromise
- No public indicators of compromise have been published for CVE-2025-31356. Exploitation would occur at the hypervisor and firmware layers, leaving limited traces in guest-level telemetry.
- Unexpected changes to hypervisor binaries, TDX module versions, or platform firmware on TDX-enabled hosts warrant investigation.
Detection Strategies
- Inventory hosts using Intel TDX and correlate installed TDX module and microcode versions against the fixed versions listed in Intel advisory SA-01419.
- Monitor privileged access to hypervisor management interfaces and TDX configuration paths, since exploitation requires prior privileged control of the host software stack.
- Alert on unsigned or unexpected kernel modules, hypervisor extensions, or platform updates on confidential-computing hosts.
Monitoring Recommendations
- Collect firmware, BIOS, microcode, and TDX module version telemetry from confidential-computing hosts and centralize it for drift detection.
- Audit administrative sessions on hosts running TDX-protected workloads and flag out-of-band configuration changes.
- Track vendor advisory feeds for Intel TDX updates and correlate patch deployment status with your confidential-computing inventory.
How to Mitigate CVE-2025-31356
Immediate Actions Required
- Identify all hosts and platforms that enable Intel TDX and confirm exposure against Intel advisory SA-01419.
- Apply Intel-provided TDX module, microcode, and BIOS updates as they become available from your platform vendor.
- Restrict administrative and system-software access on TDX-enabled hosts to reduce the population of actors who could meet the privileged-access precondition.
Patch Information
Intel has published guidance and fixed component versions in the Intel Security Advisory SA-01419. Platform owners should obtain updated TDX modules, microcode, and BIOS packages from their OEM or cloud provider and deploy them through standard firmware and hypervisor update processes.
Workarounds
- Where patching is not immediately possible, limit deployment of highly sensitive workloads on affected TDX-enabled hosts until updates are applied.
- Enforce strict separation of duties and multi-party control for privileged operations on confidential-computing hosts.
- Validate the integrity of hypervisor, firmware, and TDX components using vendor-supplied attestation and measured-boot mechanisms.
# Example: verify installed microcode revision on a Linux host
grep -m1 'microcode' /proc/cpuinfo
# Example: list loaded kernel modules relevant to virtualization for review
lsmod | grep -E 'kvm|tdx'
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
