CVE-2021-22735
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 · uneditedImproper Verification of Cryptographic Signature vulnerability exists inhomeLYnk (Wiser For KNX) and spaceLYnk V2.60 and prior which could allow remote code execution when unauthorized code is copied to the device.
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 confidenceA cryptographic signature verification flaw in homeLYnk and spaceLYnk V2.60 and prior allows attackers to bypass signature checks when copying unauthorized code to the device, enabling remote code execution without proper authentication.
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<= 2.6.0<= 2.6.0CVSS 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
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:H/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 checksWork through these to decide whether this CVE applies to you.
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Identify the device modelDetermine if the target device is a Schneider Electric Spacelynk or Homelynk controller. Check the device label, web interface, or management console for the model name.Affected if Device is a Spacelynk or Homelynk controller
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Check the installed firmware versionAccess the device web interface (typically via IP address) and navigate to the Settings or About section to view the firmware version. Alternatively, use the device's administration console or SNMP query to retrieve the firmware version.Affected if Firmware version is 2.6.0 or lower
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Verify if remote code upload is accessibleCheck if the device has exposed network services that allow code or configuration file uploads (such as FTP, SCP, HTTP file upload endpoints, or API endpoints for firmware/configuration updates). Attempt to identify accessible upload interfaces from the network.Affected if Remote code upload interfaces are exposed and accessible on the network
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Test for signature bypassIf upload interfaces are accessible, attempt to upload a modified configuration or script file (in a controlled, authorized test environment only) to observe if the device accepts files without proper cryptographic signature validation.Affected if Device accepts and executes unsigned or modified code files
The environment is affected if the device is a Schneider Electric Spacelynk or Homelynk with firmware version 2.6.0 or lower, and the device exposes network-accessible interfaces for code or configuration uploads.
Generated from the published advisory. Verify against your own configuration.
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 dataUpgrade to a patched version that implements proper cryptographic signature verification for all code/images before execution, and restrict physical/network access to prevent unauthorized code uploads.
- Consultation4.0 h
- Implementation16.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,960.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-22735 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-22735 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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