CVE-2025-3770 Overview
CVE-2025-3770 is a protection mechanism failure vulnerability [CWE-693] in EDK2, the open-source UEFI reference implementation maintained by TianoCore. An attacker with local access can bypass BIOS-level protection mechanisms to execute arbitrary code within the firmware boundary. Successful exploitation compromises confidentiality, integrity, and availability of the affected system.
Because EDK2 forms the basis for many vendor UEFI firmware distributions, this vulnerability has broad downstream impact across systems that consume the reference code.
Critical Impact
A local attacker with low privileges can defeat firmware-level protection controls, leading to arbitrary code execution in the pre-OS environment and full compromise of the affected platform.
Affected Products
- TianoCore EDK2 (UEFI reference implementation)
- Vendor BIOS/UEFI firmware built on affected EDK2 revisions
- Downstream platforms integrating vulnerable EDK2 modules
Discovery Timeline
- 2025-08-07 - CVE-2025-3770 published to the National Vulnerability Database
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-3770
Vulnerability Analysis
The vulnerability resides in the BIOS layer implemented by EDK2 and is categorized as a Protection Mechanism Failure [CWE-693]. Protection mechanisms in UEFI firmware include SMM (System Management Mode) isolation, secure boot verification, variable authentication, and register lockdowns. When one of these controls fails to enforce its intended boundary, an attacker can operate outside the trust envelope the firmware is designed to guarantee.
The attack requires local access and low privileges, but exploitation complexity is high. This suggests the attacker must satisfy specific timing, configuration, or state conditions to defeat the protection control. Once the mechanism is bypassed, the attacker can execute arbitrary code with firmware-level authority, granting persistence below the operating system.
Root Cause
The root cause is a missing or incomplete protection check within an EDK2 module that governs a sensitive firmware operation. Rather than a memory corruption bug, the flaw is a design or implementation gap that allows a privileged action to proceed without the safeguard the specification requires. Full technical detail is published in the GitHub Security Advisory GHSA-vx5v-4gg6-6qxr.
Attack Vector
Exploitation requires local access to the target platform. An authenticated user with low privileges triggers the vulnerable firmware path, causing the protection mechanism to fail open. The attacker then executes code in the firmware context, which can be used to install bootkits, tamper with Secure Boot state, or persist across operating system reinstalls.
No public proof-of-concept has been released, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Refer to the vendor advisory for exploitation specifics rather than synthetic code samples.
Detection Methods for CVE-2025-3770
Indicators of Compromise
- Unexpected changes to UEFI variables, boot order entries, or Secure Boot configuration
- Firmware measurement (PCR) values in TPM logs that deviate from a known-good baseline
- Unsigned or unrecognized DXE/SMM modules appearing after boot
Detection Strategies
- Compare firmware images and NVRAM state against vendor-provided reference hashes after each boot cycle
- Enable and monitor Windows Defender System Guard, Linux fwupd attestation, or equivalent platform integrity telemetry
- Correlate local privilege escalation attempts with subsequent firmware-touching operations in endpoint logs
Monitoring Recommendations
- Ingest UEFI and TPM event logs into a centralized SIEM for baseline deviation analysis
- Alert on driver load events referencing SMM or DXE handlers outside the expected firmware manifest
- Track BIOS version and configuration drift across the fleet using endpoint management tooling
How to Mitigate CVE-2025-3770
Immediate Actions Required
- Inventory systems running EDK2-derived firmware and identify OEM BIOS versions in use
- Apply BIOS/UEFI updates from hardware vendors as soon as patched firmware becomes available
- Restrict local access to sensitive systems and enforce least privilege for local accounts
Patch Information
The upstream fix is tracked in the TianoCore EDK2 GitHub Security Advisory GHSA-vx5v-4gg6-6qxr. Downstream OEMs must integrate the patched EDK2 commits into their firmware builds and publish updated BIOS images. Consult each hardware vendor's security bulletin for platform-specific update packages and deployment guidance.
Workarounds
- Enforce full-disk encryption with TPM-bound keys so pre-boot tampering invalidates access to data at rest
- Enable Secure Boot, BIOS administrator passwords, and physical chassis intrusion detection where supported
- Restrict administrative local logon rights and require multi-factor authentication for privileged users
# Example: verify Secure Boot state and current firmware version on Linux
mokutil --sb-state
dmidecode -s bios-version
dmidecode -s bios-release-date
# Example: capture TPM event log for baseline comparison
cat /sys/kernel/security/tpm0/binary_bios_measurements > baseline.bin
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
