dbcve.org
Gecko Software Development KitApplication · Silabs

CVE-2023-4020

CRITICAL · 9.1 CVSS v3.1 Published 2023-12-15
Fix available
A fix is available. Upgrade to 4.4.0 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
An unvalidated input in a library function responsible for communicating between secure and non-secure memory in Silicon Labs TrustZone implementation allows reading/writing of memory in the secure region of memory from the non-secure region of memory.

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

An input validation flaw in the TrustZone boundary function for secure/non-secure memory communication in Silicon Labs devices allows a non-secure world attacker to bypass memory access controls and read/write arbitrary data to the secure region of memory.

MitigationApply vendor-supplied firmware patches from Silicon Labs that implement proper input validation at the TrustZone boundary; until patched, isolate affected devices on restricted networks and limit physical access.

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
Gecko Software Development KitApplication
Affected:>= 1.0.0, < 4.4.0

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
None

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

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 Silicon Labs Gecko SDK usage
    Determine if your device or firmware is built using Silicon Labs Gecko Software Development Kit. Check firmware documentation, build files, or SDK headers for 'Silicon Labs' or 'Gecko SDK' references.
    Affected if Device does not use Silicon Labs Gecko SDK - not affected. Device uses Gecko SDK - continue to version check.
  2. Determine installed Gecko SDK version
    Check your firmware build artifacts, release notes, or SDK installation directory for the exact version number. Common locations: SDK release.txt, version.h, or embedded in firmware metadata.
    Affected if Version is >= 1.0.0 and < 4.4.0 - potentially affected. Version is unknown or cannot be determined - treat as potentially affected.
  3. Verify TrustZone is enabled
    Examine your firmware configuration for TrustZone settings. Check project configuration files (e.g., .slcp, .emProject), linker scripts, or hardware initialization code for TrustZone-related flags such as 'ARM_MPU', 'TZ_ENABLED', or secure/non-secure memory region definitions.
    Affected if TrustZone is not configured or disabled - likely not vulnerable to this specific boundary bypass flaw. TrustZone is enabled - continue to affected version check.
  4. Confirm secure world access capability
    Review firmware code that interacts with TrustZone boundary functions, particularly secure/non-secure callable interfaces. Check if non-secure world code can invoke secure region functions or if there are memory-mapped I/O accesses to secure regions.
    Affected if Non-secure code has a path to invoke TrustZone boundary functions - vulnerable to bypass. No TrustZone boundary interfaces exist - not affected.

Device is affected if it uses Silicon Labs Gecko SDK version 1.0.0 through 4.3.x AND has TrustZone enabled with non-secure to secure communication paths. If either the SDK version is >= 4.4.0 or TrustZone is not used, the device is not affected by this vulnerability.

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 4.4.0 or later
Fixed in 4.4.0
Interim mitigation

Apply vendor-supplied firmware patches from Silicon Labs that implement proper input validation at the TrustZone boundary; until patched, isolate affected devices on restricted networks and limit physical access.

Recommended fix High confidence

Gecko SDK 4.4.0 or later

  1. 1. Identify all deployments of Silicon Labs Gecko SDK in your development environment and build pipelines
  2. 2. Verify current Gecko SDK version using your package manager or SDK management tool
  3. 3. Download and install Gecko SDK version 4.4.0 or later from Silicon Labs website or official repository
  4. 4. Rebuild all affected applications that use the TrustZone functionality
  5. 5. Retest secure/non-secure memory boundary operations to ensure functionality is preserved
  6. 6. Update any pinned dependency references in build configurations to specify version >= 4.4.0

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

Fix this in Gecko Software Development Kit Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA8.0 h
44.0 hours of engineering $7,720
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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-2023-4020 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