CVE-2025-31936 Overview
CVE-2025-31936 affects certain Intel Xeon 6 processors that support Intel Trust Domain Extensions (TDX). The flaw stems from improper handling of overlap between protected memory ranges when TDX is used within System Management Mode (SMM). An attacker operating from SMM with privileged access can leverage the overlap condition to escalate privileges further. Successful exploitation impacts the confidentiality and integrity of the affected system. The vulnerability is tracked under CWE-1260: Improper Handling of Overlap Between Protected Memory Ranges and is documented in Intel Security Advisory SA-01379.
Critical Impact
An SMM-privileged adversary can escalate privileges on affected Intel Xeon 6 processors, compromising the confidentiality and integrity of TDX-protected memory.
Affected Products
- Select Intel Xeon 6 processors supporting Intel TDX
- Systems using Intel TDX within System Management Mode (SMM)
- Server platforms relying on TDX-based confidential computing enclaves
Discovery Timeline
- 2026-08-11 - CVE-2025-31936 published to the National Vulnerability Database
- 2026-08-12 - Last updated in the NVD database
Technical Details for CVE-2025-31936
Vulnerability Analysis
Intel TDX establishes trust domains with hardware-enforced memory isolation. SMM is a highly privileged CPU operating mode used for firmware-level tasks. On affected Intel Xeon 6 processors, the processor does not correctly enforce boundaries when protected memory ranges overlap while TDX operations execute inside SMM context.
An SMM-privileged adversary can manipulate this overlap condition to access or modify memory regions that should remain isolated. The result is escalation of privilege affecting the confidentiality and integrity of the platform, though availability is not impacted. Exploitation requires local access, high attack complexity, and specialized internal knowledge of the affected microarchitecture.
Root Cause
The root cause is improper handling of overlap between protected memory ranges [CWE-1260]. When TDX-protected regions and SMM-protected regions overlap, the hardware fails to enforce the strictest access control, allowing SMM code to interact with TDX-protected memory in unintended ways.
Attack Vector
The attack is local and requires the attacker to already hold SMM-level privileges. This typically implies a prior firmware compromise or supply chain foothold. The attacker must also possess specialized internal knowledge of processor behavior and be capable of orchestrating a high-complexity exploitation sequence. No user interaction is required. Refer to the Intel Security Advisory SA-01379 for platform-specific details.
Detection Methods for CVE-2025-31936
Indicators of Compromise
- Unexpected modifications to SMM firmware or SMI handler code on Intel Xeon 6 platforms.
- Anomalous access patterns to TDX-protected memory regions reported by platform firmware telemetry.
- Firmware or BIOS versions that do not match vendor-published, patched baselines.
Detection Strategies
- Validate platform firmware integrity using vendor-provided attestation and measured boot mechanisms.
- Monitor Intel TDX attestation reports for unexpected changes in trust domain measurements.
- Correlate firmware update events with authorized change management records to identify unauthorized flashing.
Monitoring Recommendations
- Ingest server firmware and BMC logs into a centralized SIEM for anomaly analysis.
- Track hardware inventory to identify systems running affected Intel Xeon 6 SKUs pending microcode updates.
- Alert on TDX attestation failures or unexpected reboots into recovery firmware.
How to Mitigate CVE-2025-31936
Immediate Actions Required
- Identify all Intel Xeon 6 systems in the environment that enable Intel TDX for confidential computing workloads.
- Apply the microcode and BIOS updates referenced in Intel Security Advisory SA-01379 as soon as vendor-signed firmware becomes available.
- Restrict physical and administrative access to affected servers to reduce the likelihood of SMM-level compromise.
Patch Information
Intel has published guidance in Intel Security Advisory SA-01379. Platform vendors distribute the corresponding microcode and BIOS updates for affected Xeon 6 processors. Apply the OEM-provided firmware updates for each server model to remediate the improper memory range overlap handling.
Workarounds
- Disable Intel TDX on affected systems where confidential computing is not required until patched firmware is deployed.
- Enforce strict signing and verification of all SMM and BIOS firmware components to prevent unauthorized SMI handlers.
- Limit administrative and out-of-band management access to trusted operators and networks.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
