CVE-2021-3384
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 · uneditedA vulnerability in Stormshield Network Security could allow an attacker to trigger a protection related to ARP/NDP tables management, which would temporarily prevent the system to contact new hosts via IPv4 or IPv6. This affects versions 2.0.0 to 2.7.7, 2.8.0 to 2.16.0, 3.0.0 to 3.7.16, 3.8.0 to 3.11.4, and 4.0.0 to 4.1.5. Fixed in versions 2.7.8, 3.7.17, 3.11.5, and 4.2.0.
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 vulnerability in Stormshield Network Security allows an attacker to trigger ARP/NDP table protection mechanisms, causing temporary denial of service by preventing the system from contacting new IPv4 or IPv6 hosts. This is a resource exhaustion or protection bypass issue affecting network connectivity functionality.
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>= 2.0.0, < 2.7.8>= 2.8.0, <= 2.16.0>= 3.0.0, <= 3.7.17>= 3.8.0, <= 3.11.5>= 4.0.0, < 4.1.5CVSS 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
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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 Stormshield Network Security versionAccess the Stormshield CLI or admin web interface and run the command to display the firmware version, typically 'show system' or check the dashboard for the version numberAffected if The displayed version falls within any of these ranges: 2.0.0 to 2.7.7, 2.8.0 to 2.16.0, 3.0.0 to 3.7.17, 3.8.0 to 3.11.5, or 4.0.0 to 4.1.4
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Confirm IPv4 or IPv6 networking is configuredCheck the network configuration for any active IPv4 or IPv6 interfaces using 'show ip interface' or similar command in the Stormshield CLIAffected if Any IPv4 or IPv6 interfaces are configured and active on the device
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Review ARP/NDP cache behaviorExamine the ARP or NDP cache using 'show arp' and 'show ndp' commands to observe if new host entries are being added or blockedAffected if New IPv4 or IPv6 host entries fail to populate in the ARP/NDP table after initial network activity
You are affected if your Stormshield Network Security version is within the affected ranges listed AND IPv4 or IPv6 networking is enabled, causing inability to contact new hosts due to ARP/NDP table protection triggers.
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 data2.7.84.1.5
Upgrade Stormshield Network Security to fixed versions 2.7.8, 3.7.17, 3.11.5, or 4.2.0 as specified in the vendor advisory to resolve the vulnerability.
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-3384 — 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-2021-3384 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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