CVE-2025-4275Public exploit

Secure Boot bypass via untrusted NVRAM certificate

Published Jun 11, 2025 · Updated Aug 14, 2025

Improper access control in InsydeH2O UEFI BIOS allows local users to bypass Secure Boot and execute attacker-signed UEFI code. SecurityStubDxe reads SecureFlashSetupMode and SecureFlashCertData without confirming that firmware created them as volatile variables, so attacker-created nonvolatile values become trusted. The attack requires local access able to write firmware variables; successful exploitation runs malicious code before the operating system and can persist below endpoint controls.

CVSS severity7.8
High
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in InsydeH2O UEFI BIOS allows local users to bypass Secure Boot and execute attacker-signed UEFI code. SecurityStubDxe reads SecureFlashSetupMode and SecureFlashCertData without confirming that firmware created them as volatile variables, so attacker-created nonvolatile values become trusted. The attack requires local access able to write firmware variables; successful exploitation runs malicious code before the operating system and can persist below endpoint controls.

The record

CVE
CVE-2025-4275
Published
Jun 11, 2025
Updated
Aug 14, 2025
Vendor
Insyde Software
Product
InsydeH2O UEFI BIOS
Classifications
CWE-284, T1542.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 11, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 14, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Kernel 5.2 <05.2A.16
  2. Affected versionversion=Kernel 5.3 <05.39.16
  3. Affected versionversion=Kernel 5.4 <05.47.16
  4. Affected versionversion=Kernel 5.5 <05.55.16
  5. Affected versionversion=Kernel 5.6 <05.62.16
  6. Affected versionversion=Kernel 5.7 <05.71.16

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Insyde Software · InsydeH2O UEFI BIOSversion=Kernel 5.2 <05.2A.16; version=Kernel 5.3 <05.39.16; version=Kernel 5.4 <05.47.16; version=Kernel 5.5 <05.55.16; version=Kernel 5.6 <05.62.16; version=Kernel 5.7 <05.71.16

Published CVSS scores

7.8Insyde SoftwareCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-284Improper Access Control
T1542.001Pre-OS Boot: System Firmware

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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