CVE-2025-21094: Intel Server Board UEFI Privilege Escalation

CVE-2025-21094 Overview

CVE-2025-21094 is an improper input validation vulnerability [CWE-20] in the Unified Extensible Firmware Interface (UEFI) firmware Driver Execution Environment (DXE) module for Intel Server D50DNP and M50FCP boards. A privileged local user can leverage the flaw to escalate privileges on affected systems. Intel disclosed the issue in security advisory SA-01269.

The vulnerability affects platform firmware, which executes before the operating system loads. Successful exploitation grants attackers control at a layer beneath OS-level security controls. Persistence at the firmware level survives operating system reinstalls and disk replacements.

Critical Impact
A privileged local attacker can escalate privileges by abusing a DXE module that fails to validate input, gaining execution at UEFI firmware level on affected Intel server platforms.

Affected Products

Intel Server Board D50DNP family UEFI firmware
Intel Server Board M50FCP family UEFI firmware
DXE modules within the Intel platform firmware stack for these boards

Discovery Timeline

2025-05-13 - CVE-2025-21094 published to the National Vulnerability Database
2026-06-17 - Last updated in the NVD database

Technical Details for CVE-2025-21094

Vulnerability Analysis

The flaw resides in a DXE module of the UEFI firmware shipped with Intel Server D50DNP and M50FCP boards. DXE drivers run during platform initialization and expose services through UEFI protocols and System Management Mode (SMM) interfaces. When a DXE module accepts caller-controlled input without validation, an attacker with existing privilege can supply malformed data to influence firmware execution paths.

The attack requires local access and high privileges, meaning the attacker must already hold administrative rights on the host. The consequence is elevation to firmware-level execution, which sits below the operating system trust boundary. That transition breaks the isolation between OS-level administrators and platform firmware code.

Root Cause

The root cause is improper input validation [CWE-20] within a DXE driver. The module processes attacker-influenced parameters, such as buffer pointers, sizes, or configuration structures, without enforcing expected ranges, types, or memory boundaries. This category of firmware defect commonly enables memory corruption, arbitrary write primitives, or logic bypasses inside the UEFI environment.

Attack Vector

Exploitation requires local access with high privileges and no user interaction. An attacker running as administrator or root invokes the vulnerable DXE interface, either through runtime UEFI services, an SMM communication buffer, or a firmware configuration path exposed to the OS. Malformed input drives the DXE module into a state that yields privilege escalation into firmware context. Full technical mechanics are limited to the vendor advisory; consult the Intel Security Advisory SA-01269 for validated details.

Detection Methods for CVE-2025-21094

Indicators of Compromise

Unexpected changes to UEFI variables, boot order, or Secure Boot policy on D50DNP or M50FCP servers.
Firmware version strings that do not match the vendor-published fixed build for the affected board.
Unsigned or unknown DXE drivers observed in firmware measurements or TPM Platform Configuration Register (PCR) logs.

Detection Strategies

Collect and baseline firmware measurements using the Trusted Platform Module and compare PCR values across the fleet to detect drift.
Run vendor firmware integrity tools such as CHIPSEC on affected boards to identify unexpected DXE modules or SMM handlers.
Correlate administrative sessions on affected hosts with subsequent firmware update, efibootmgr, or flashrom activity in operating system logs.

Monitoring Recommendations

Alert on any process invoking UEFI variable write APIs or firmware capsule updates outside approved change windows.
Track BMC and IPMI activity on Intel server boards for out-of-band firmware modifications tied to privileged accounts.
Ingest platform event logs and hardware inventory data into a centralized data lake to detect firmware version anomalies at scale.

How to Mitigate CVE-2025-21094

Immediate Actions Required

Inventory all Intel Server D50DNP and M50FCP boards and record their current BIOS and UEFI firmware versions.
Apply the firmware update referenced in Intel Security Advisory SA-01269 to every affected board.
Restrict local administrative access on affected servers and enforce multi-factor authentication for privileged accounts.
Enable Secure Boot, BIOS write protection, and administrator BIOS passwords where operationally feasible.

Patch Information

Intel published fixed firmware for the affected Server D50DNP and M50FCP boards in advisory SA-01269. Administrators should download the updated BIOS or system firmware package from Intel's support site for the specific board model and apply it through the vendor's supported update process. Validate the firmware version after installation to confirm remediation.

Workarounds

Limit the number of accounts with local administrative privilege on affected servers to reduce the exploitable population.
Enforce hardware-rooted attestation, such as TPM-based measured boot, to detect unauthorized firmware modification.
Disable unused UEFI runtime services and out-of-band management interfaces where the workload permits.

bash

# Example: verify installed BIOS version on a Linux host to confirm patch level
sudo dmidecode -s bios-version
sudo dmidecode -s bios-release-date
sudo dmidecode -s baseboard-product-name