CVE-2021-25846
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 ChassisID TLV in userdisk/vport_lldpd in Moxa Camera VPort 06EC-2V Series, version 1.1, allows attackers to cause a denial of service due to a negative number passed to the memcpy function 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 confidenceThe Moxa Camera VPort 06EC-2V Series version 1.1 contains a vulnerability in its LLDP (Link Layer Discovery Protocol) implementation (userdisk/vport_lldpd). The ChassisID TLV field is not properly validated before being used in a memcpy() call. An attacker can send a crafted LLDP packet containing a negative number in the ChassisID field, which causes memcpy to interpret it as a large unsigned value, leading to a denial of service (crash or hang).
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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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.
-
Identify the device modelLocate the Moxa VPort camera on the network and verify it is a 06EC-2V series model (06ec-2v26m, 06ec-2v36m, 06ec-2v36m Ct, 06ec-2v36m Ct T, 06ec-2v42m, 06ec-2v42m T, 06ec-2v42m Ct, or 06ec-2v42m Ct T)Affected if The device is a Moxa VPort 06EC-2V series camera
-
Check the firmware versionAccess the device web interface or use SNMP to retrieve the firmware version. Compare it against the affected range: version 1.1 or lowerAffected if The installed firmware is version 1.1 or lower
-
Verify LLDP is enabledCheck the device configuration via its web interface to determine if LLDP (Link Layer Discovery Protocol) is turned on. The vulnerability exists in the userdisk/vport_lldpd componentAffected if LLDP is enabled on the device
-
Check UDP port 3498 accessibilityScan the device network to determine if UDP port 3498 (the LLDP service port) is reachable from untrusted network segmentsAffected if UDP port 3498 is exposed to attackers on the network
A device is affected if it is a Moxa VPort 06EC-2V series camera running firmware version 1.1 or lower with LLDP enabled and UDP port 3498 accessible from an untrusted network.
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 dataIf vendor firmware updates are available, apply them promptly. Otherwise, restrict network access to the affected device's LLDP service (typically UDP port 3498) through network segmentation or firewall rules to prevent unauthenticated attackers from sending malicious LLDP packets.
- Consultation4.0 h
- Implementation8.0 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 $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-25846 — 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-2021-25846 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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