The vendor has published a fix. Version details are below where the sources state them.
Steps
Written by AI from the record
Check whether your device firmware is InsydeH2O and whether you can confirm the current firmware version with your IT process (e.g., via vendor tools or system inventory).
Verify the device runs Linux kernels in the affected maintenance lines (5.3, 5.4, 5.5, or 5.6) because the published remediation is kernel-version specific.
If you cannot upgrade right away, restrict who can access local machine admin/firmware settings and harden physical and local login controls immediately, since high local privileges are required.
UEFI BIOS embedded Shell could be used to bypass Secure Boot via shell commands or startup scripts.
In plain language
Written by AI from the record
If your business uses devices with InsydeH2O firmware, a high-privilege local attacker may be able to use a built-in startup shell to bypass Secure Boot; this is serious but it’s not likely to be triggered remotely.
InsydeH2O UEFI firmware has a weakness (CWE-489) where the embedded Shell can be used to bypass Secure Boot protection using shell commands or startup scripts; the attack requires high local privileges and does not require user interaction.
If you're affected
Boot-time security bypass
Malware persistence at startup
Full system compromise
Ransomware enablement
What is it
Secure Boot is like a gatekeeper that helps ensure only trusted software can start when the computer boots. This issue is a way to get around that gatekeeper using the firmware’s built-in startup shell—so a determined attacker who already has strong local access could potentially make malicious code run at boot. Think of it as finding a door inside the building that lets someone bypass the front-desk security check.
Who is affected
This matters if you operate devices that use InsydeH2O UEFI firmware. It’s relevant when someone with high privileges on the local machine can reach the UEFI BIOS environment. It’s not a typical “internet attack” because the findings indicate local access and high privileges are required.
How urgent is it
This is a RED issue because an attacker who already has high-level local access can bypass Secure Boot, enabling deeper compromise and startup persistence. Even though remote exploitation isn’t established in the findings, local attackers (including insiders or those who already landed on a machine) can use it to significantly weaken the boot security chain.
What to do — in detail
Confirm exposure:
Identify which machines use InsydeH2O firmware (from your system inventory, device management console, or vendor documentation).
Check which kernel maintenance line(s) you run (5.3, 5.4, 5.5, 5.6), since the published remediation is given as specific kernel version identifiers.
Document the current firmware/kernel versions so you can prove you moved off the affected configuration after patching.
Apply the fix:
If you run Kernel 5.3, upgrade to version 05.3A.25.
If you run Kernel 5.4, upgrade to version 05.48.25.
If you run Kernel 5.5, upgrade to version 05.56.25.
If you run Kernel 5.6, upgrade to version 05.63.25.
Upgrade notes / breaking change considerations:
Follow your standard kernel upgrade procedure for your distribution and test on a staging machine if you have one (especially if you run production servers).
Plan maintenance windows as needed for reboot, since kernel changes typically require it.
If patching is delayed:
Immediately reduce the chance that a local attacker can get “high privileges,” because that is the stated precondition for reaching the UEFI BIOS environment.
Enforce stronger local authentication controls, limit admin accounts, and restrict physical access to machines (since the attack vector is local).
What to monitor:
After changes, ensure reboots complete normally and that device inventory reflects the updated versions.
Review local security logs for unusual firmware/boot-time activity, especially events tied to privileged access and BIOS/UEFI entry (exact log sources depend on your environment).
CISA KEV note:
This CVE is not listed in the provided CISA KEV findings, and the findings do not show a clear dated press claim of exploitation.
Technical context
Severity/intent:
The weakness is described as bypassing Secure Boot protection mechanisms, using the UEFI embedded Shell.
Mechanism (how it’s triggered):
An attacker with high-level local privileges can execute shell commands or startup scripts in the built-in computer startup shell within the UEFI environment to bypass Secure Boot checks.
Attack vector and requirements:
Attack vector is local; user interaction is none; high authentication/privilege level is required.
Exploitation status:
No public exploit code was found in the provided findings.
No clear dated real-world exploitation claim is present in the provided news findings.
KEV listing is not shown.
EPSS is provided as a prediction in the findings (do not treat as proof of exploitation).
Remediation:
Published vendor remediation is kernel-version specific for Kernel 5.3/5.4/5.5/5.6 with the exact version identifiers listed in the findings.
This is a general assessment based on public vulnerability data. It does not account for your specific infrastructure — when in doubt, consult a security specialist.
