CVE-2025-31944: Intel TDX Module Race Condition DoS Flaw

CVE-2025-31944 Overview

CVE-2025-31944 is a race condition vulnerability affecting Intel Trust Domain Extensions (TDX) Module versions prior to tdx1.5. The vulnerability exists within Ring 0 (Hypervisor level) and can be exploited by an authorized adversary with privileged user access to cause a denial of service condition. This vulnerability requires local access, high attack complexity, and specific attack prerequisites to be present for successful exploitation.

Critical Impact

Privileged attackers with local access can exploit this race condition to cause denial of service, potentially disrupting virtualized workloads and confidential computing environments protected by Intel TDX technology.

Affected Products

• Intel TDX Module versions prior to tdx1.5
• Systems utilizing Intel Trust Domain Extensions for confidential computing
• Hypervisor environments leveraging TDX for workload isolation

Discovery Timeline

• 2026-02-10 - CVE-2025-31944 published to NVD
• 2026-02-10 - Last updated in NVD database

Technical Details for CVE-2025-31944

Vulnerability Analysis

This vulnerability is classified under CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization), commonly known as a race condition. The flaw resides in the Intel TDX Module, which provides hardware-based isolation for confidential computing workloads through Trust Domains.

The race condition occurs within Ring 0 operations, specifically in the hypervisor context where the TDX Module manages secure memory and execution states for Trust Domains. When specific timing conditions are met, concurrent operations can interfere with each other, leading to an inconsistent state that results in denial of service.

The vulnerability requires a privileged user with local access to the system, combined with the ability to trigger specific timing-dependent operations. While the primary impact is high availability disruption, subsequent system availability may also experience low-level degradation. Confidentiality and integrity are not affected by this vulnerability.

Root Cause

The root cause is improper synchronization during concurrent execution within the TDX Module's Ring 0 operations. The module fails to properly handle simultaneous access to shared resources, creating a Time-of-Check Time-of-Use (TOCTOU) window that can be exploited under specific conditions.

Race conditions in hypervisor-level code are particularly concerning as they affect the foundational security layer responsible for isolating confidential workloads. The TDX Module's failure to implement adequate locking mechanisms or atomic operations during critical sections enables this vulnerability.

Attack Vector

The attack requires local access to the vulnerable system and privileged user permissions. An attacker must:

1. Obtain privileged access to a system running an affected TDX Module version
2. Identify the specific timing window where the race condition can be triggered
3. Execute carefully timed operations to exploit the synchronization flaw
4. Cause the TDX Module to enter an inconsistent state resulting in denial of service

The high complexity requirement indicates that successful exploitation is non-trivial and requires precise timing and knowledge of the system's internal state. The attack does not require user interaction but does require specific attack prerequisites to be present.

Due to the nature of this vulnerability, no verified code examples are available. The race condition exists within proprietary Intel TDX Module code at the hypervisor level. Technical details can be found in the Intel Security Advisory SA-01397.

Detection Methods for CVE-2025-31944

Indicators of Compromise

• Unexpected crashes or restarts of Trust Domain workloads without clear application-level cause
• System logs indicating TDX Module errors or hypervisor-level synchronization failures
• Abnormal patterns in privileged process execution timing around TDX operations
• Repeated denial of service events affecting confidential computing workloads

Detection Strategies

• Monitor system event logs for TDX Module errors and hypervisor exceptions at Ring 0
• Implement behavioral analysis to detect unusual patterns of privileged operations targeting TDX functionality
• Deploy endpoint detection solutions capable of monitoring hypervisor-level activity and Trust Domain state changes
• Correlate timing anomalies with privileged user activity to identify potential exploitation attempts

Monitoring Recommendations

• Enable detailed logging for Intel TDX Module operations and hypervisor events
• Configure alerts for unexpected Trust Domain terminations or state inconsistencies
• Monitor privileged user activity on systems running TDX-enabled workloads
• Implement continuous integrity monitoring for TDX Module configuration and state

How to Mitigate CVE-2025-31944

Immediate Actions Required

• Identify all systems running Intel TDX Module versions prior to tdx1.5
• Review privileged user access to TDX-enabled systems and implement least-privilege principles
• Schedule maintenance windows to apply the TDX Module update to version tdx1.5 or later
• Increase monitoring on affected systems until patches can be applied

Patch Information

Intel has addressed this vulnerability in TDX Module version tdx1.5 and later. Organizations should update their TDX Module to the latest available version as recommended in the Intel Security Advisory SA-01397.

The patch implements proper synchronization mechanisms to prevent the race condition from occurring during concurrent Ring 0 operations. Contact Intel or your hardware vendor for specific update procedures applicable to your deployment environment.

Workarounds

• Restrict privileged user access to TDX-enabled systems to trusted personnel only
• Implement additional access controls and monitoring for hypervisor-level operations
• Consider temporarily isolating critical confidential computing workloads until patches are applied
• Enable enhanced audit logging for all privileged operations on affected systems

# Verify TDX Module version (example command structure may vary by platform)
# Consult Intel documentation for specific version verification procedures
dmesg | grep -i "tdx"
# Check for TDX Module version information in system logs
journalctl -k | grep -i "tdx module"