CVE-2021-25847
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 validation of the length field of LLDP-MED TLV in userdisk/vport_lldpd in Moxa Camera VPort 06EC-2V Series, version 1.1, allows information disclosure to attackers due to controllable loop counter variable via a crafted lldp packet.
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 confidenceBuffer handling vulnerability in the LLDP-MED TLV parser (userdisk/vport_lldpd) allows an attacker to control the loop counter via a malformed length field in a crafted LLDP packet, leading to information disclosure through out-of-bounds read operations.
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<= 1.1<= 1.1<= 1.1<= 1.1<= 1.1<= 1.1<= 1.1<= 1.1CVSS 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
- None
- Availability
- High
CVSS:3.1/AV:N/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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Identify the Moxa Vport modelLocate the device model number on the physical device label or in the web management interface under Device Information. Confirm it is one of the following: Vport 06ec 2v26m, 2v36m, 2v36m T, 2v36m Ct, 2v36m Ct T, 2v42m, 2v42m T, 2v42m Ct, or 2v42m Ct T.Affected if The device is a Moxa Vport from the 06ec series listed above.
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Check the firmware versionIn the device web interface, navigate to System Settings > Firmware Upgrade or System Information page. Note the firmware version displayed. Compare it to the affected range: all versions <= 1.1.Affected if The installed firmware version is 1.1 or lower.
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Verify if LLDP is enabledIn the device web interface, go to Network Settings > LLDP or Layer 2 Settings. Check whether LLDP (Link Layer Discovery Protocol) is enabled or disabled.Affected if LLDP is enabled on the device.
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Assess network exposure to untrusted LLDP packetsReview network segmentation and access controls. Determine whether the device is connected to untrusted networks where an attacker could inject malformed LLDP packets.Affected if The device is reachable from untrusted network segments without port-based isolation.
A user is affected if they have a Moxa Vport 06ec series device with firmware version 1.1 or lower, with LLDP enabled, and accessible from a network where an attacker can send crafted LLDP packets.
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 vendor firmware update if available; otherwise disable LLDP on affected devices or isolate them via network segmentation to prevent unauthorized LLDP packet injection.
- Consultation4.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,392.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-25847 — 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-2021-25847 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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