dbcve.org
Improper Input ValidationWeakness · CWE-20

CVE-2025-4276

HIGH · 7.5 CVSS v3.1 Published 2025-08-13
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
77/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
UsbCoreDxe has a vulnerability which can be used to write arbitrary memory inside SMRAM and execute arbitrary code at SMM level.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

UsbCoreDxe, a USB core driver in UEFI firmware, contains a memory corruption vulnerability that allows an attacker to write arbitrary data to SMRAM (System Management RAM) and subsequently execute code at SMM (System Management Mode) privilege level. This bypasses the SMM security boundary, giving the attacker firmware-level code execution with the highest CPU privileges.

MitigationApply the vendor-supplied firmware update containing the patched UsbCoreDxe driver. Prior to deployment, validate the firmware update in a non-production environment and verify the update is correctly applied to all affected systems.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
High
Privileges
High
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the installed UEFI firmware version
    Access the system BIOS/UEFI setup (typically via F2, F12, or Del key during boot) and record the firmware version, or use command-line tools like 'dmidecode -s bios-version' on Linux or 'wmic bios get smbiosbiosversion' on Windows
    Affected if The firmware version is older than the vendor-released patch for CVE-2025-4276 (check vendor security advisory for the corrected version number)
  2. Verify if USB support is enabled in UEFI
    Enter UEFI/BIOS settings and navigate to USB configuration options, or use 'bcdedit /enum all' on Windows or check /sys/bus/usb on Linux to confirm USB is active
    Affected if USB is enabled and the system has an exposed USB port, as the UsbCoreDxe driver processes USB device communications which triggers the vulnerable code path
  3. Confirm SMRAM (System Management RAM) is accessible
    Use the UEFI shell or OS-level tools to check SMRAM status. On some systems, 'efi-info' or specialized firmware analysis tools can reveal SMRAM configuration. Check UEFI variable 'SmmLockBox' or similar SMM-related settings
    Affected if SMRAM is not locked or is configured in an insecure state (e.g., 'Open' or 'Unlocked' status), allowing the vulnerable driver to write to SMRAM memory regions
  4. Check for the UsbCoreDxe driver version in firmware
    Extract and analyze the UEFI firmware image using tools like UEFI Toolkit, ChipSec, or vendor-provided firmware update utilities. Locate the UsbCoreDxe driver and compare its internal version against the patched driver release
    Affected if The UsbCoreDxe driver version predates the vendor's CVE-2025-4276 patch release, indicating the vulnerable code is present
  5. Identify the system vendor and model for advisory correlation
    Run 'dmidecode -s system-manufacturer' and 'dmidecode -s system-product-name' on Linux, or 'wmic computersystem get manufacturer,model' on Windows to identify the exact system model
    Affected if The system model is listed in the vendor's security advisory as affected by CVE-2025-4276, confirming potential exposure

A system is affected if it runs a firmware version containing an unpatched UsbCoreDxe driver that predates the vendor fix, has USB support enabled, and has accessible SMRAM configuration.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-supplied firmware update containing the patched UsbCoreDxe driver. Prior to deployment, validate the firmware update in a non-production environment and verify the update is correctly applied to all affected systems.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing8.0 h
  • Review / QA4.0 h
18.0 hours of engineering $3,080
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,928.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-4276 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data