CVE-2021-20024
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 · uneditedMultiple Out-of-Bound read vulnerability in SonicWall Switch when handling LLDP Protocol allows an attacker to cause a system instability or potentially read sensitive information from the memory locations.
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 confidenceAn out-of-bounds read vulnerability exists in SonicWall Switch devices when processing LLDP (Link Layer Discovery Protocol) packets. The vulnerability allows an attacker to read memory beyond allocated buffers, potentially causing system instability or exposing sensitive information from memory.
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<= 1.0.0.5-16CVSS 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
- Adjacent
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/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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Confirm device model is SonicWall SwitchAccess the switch management interface or CLI and retrieve the device model information. Check the hardware label or system info for 'SonicWall Switch' or similar designation.Affected if Device is not a SonicWall Switch - this vulnerability only affects that specific product line.
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Check installed firmware versionAccess the switch CLI or web management interface and navigate to System > Firmware or use 'show version' command in CLI. Note the firmware version number.Affected if Firmware version is 1.0.0.5-16 or any version lower than 1.0.0.5-16 (e.g., 1.0.0.5-15, 1.0.0.4, etc.).
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Verify if LLDP is enabledAccess the switch CLI or web management interface and check LLDP configuration. In CLI, use 'show lldp' or 'show lldp configuration' commands. In web interface, look for LLDP settings under Network or Interface settings.Affected if LLDP is enabled on any interface. The vulnerability triggers when the switch processes malicious LLDP packets, so LLDP must be running for the device to be at risk.
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Review LLDP interface assignmentsCheck which interfaces have LLDP transmit and receive enabled. In CLI, use 'show lldp interface' to list all interfaces with LLDP status.Affected if LLDP is enabled on externally accessible interfaces or untrusted ports.
The device is affected if it is a SonicWall Switch running firmware version 1.0.0.5-16 or lower AND has LLDP enabled on one or more interfaces.
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 dataApply the vendor-provided firmware update for SonicWall Switch devices. If patching is not immediately possible, consider disabling LLDP on vulnerable interfaces or implementing network access controls to limit LLDP traffic to trusted sources.
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20024 — 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-2021-20024 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
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