dbcve.org
Edk2Application · Tianocore

CVE-2021-38578

CRITICAL · 9.8 CVSS v3.1 Published 2022-03-03
Fix available
A fix is available. Upgrade to after 202202 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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
Existing CommBuffer checks in SmmEntryPoint will not catch underflow when computing BufferSize.

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 · moderate confidence

The vulnerability exists in UEFI SMM (System Management Mode) code where CommBuffer checks in SmmEntryPoint fail to catch underflow when computing BufferSize. This allows buffer size calculation to wrap around, potentially enabling memory corruption in SMM which operates at the highest privilege level on x86 processors.

MitigationApply vendor firmware updates that address this vulnerability; until patched, ensure Secure Boot is enabled and restrict physical access to mitigate exploitation risk.

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

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Edk2Application
Affected:<= 202202
KernelOperating system
Affected:= 5.0= 5.1= 5.2= 5.3= 5.4= 5.5

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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 your UEFI firmware version
    On Linux, run 'sudo dmidecode -s bios-version' or 'sudo dmidecode -s firmware-version'. On Windows, run 'wmic bios get smbiosbiosversion' or check System Information (msinfo32). On UEFI systems, you may need to enter BIOS setup (typically press Del/F2 during boot) to view the firmware version.
    Affected if The displayed version matches or is older than the affected versions (Edk2 <= 202202, Insyde Kernel 5.0-5.5)
  2. Identify the firmware vendor
    On Linux, run 'sudo dmidecode -s bios-vendor' or 'sudo dmidecode -s system-manufacturer'. On Windows, run 'wmic baseboard get manufacturer' or check the BIOS setup screen for vendor information. Check if your firmware is from a vendor using Tianocore Edk2 or Insyde as the firmware foundation.
    Affected if The vendor uses Tianocore Edk2 or Insyde Kernel as their firmware base, particularly for Insyde-based systems or open-source firmware implementations
  3. Confirm SMM is accessible and operational
    On Linux, check /sys/firmware/efi/systab or use 'sudo cat /proc/ioports' to look for SMM-related entries. On Windows, use MSInfo32 to check firmware type (UEFI vs BIOS) and verify System Management Mode is present. The vulnerability requires SMM to be active.
    Affected if Your system runs in UEFI mode with SMM (System Management Mode) enabled, as this is the operational context where the vulnerable code executes
  4. Cross-reference firmware version against affected ranges
    If using a Tianocore-based firmware (often found in open-source or some embedded systems), compare your version to <= 202202. If using Insyde firmware (common on many OEM laptops/desktops), compare to versions 5.0, 5.1, 5.2, 5.3, 5.4, or 5.5. Check your vendor's security advisories if version format differs.
    Affected if Your exact firmware version falls within or below the affected version numbers for either Tianocore Edk2 or Insyde Kernel

You are likely affected if your UEFI firmware is based on Tianocore Edk2 version 202202 or earlier, or Insyde Kernel versions 5.0 through 5.5, and your system uses UEFI with SMM enabled.

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.

dbcve · scoped
Upgrade available Upgrade to a release after 202202
Interim mitigation

Apply vendor firmware updates that address this vulnerability; until patched, ensure Secure Boot is enabled and restrict physical access to mitigate exploitation risk.

Recommended fix Moderate confidence

EDK2 version 202203 or later (or corresponding OEM firmware update containing the fix)

  1. 1. Identify all systems running EDK2 firmware version 202202 or earlier
  2. 2. Check with your system/OEM vendor for available firmware updates that address CVE-2021-38578
  3. 3. Apply the vendor-provided firmware update that includes the fix for the CommBuffer underflow in SmmEntryPoint
  4. 4. Verify the updated firmware version matches a fixed release (202203 or later)
  5. 5. Test the update in a non-production environment first to ensure system stability
Caveat Firmware updates carry inherent risks; ensure backup and rollback capabilities are in place before applying

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Edk2 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,600
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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-2021-38578 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