CVE-2020-16843
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 · uneditedIn Firecracker 0.20.x before 0.20.1 and 0.21.x before 0.21.2, the network stack can freeze under heavy ingress traffic. This can result in a denial of service on the microVM when it is configured with a single network interface, and an availability problem for the microVM network interface on which the issue is triggered.
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 confidenceFirecracker's network stack can freeze under heavy ingress traffic, causing a denial of service on microVMs configured with a single network interface. The vulnerability is triggered by malicious or excessive incoming network traffic that causes the network stack to become unresponsive.
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= 0.20.0= 0.21.0= 0.21.1CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:H/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.
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Identify installed Firecracker versionRun `firecracker --version` or check the firecracker binary metadata/version file on the host. If using a VM/microVM, check the version of the firecracker process or the binary used to start it.Affected if The version is 0.20.0, 0.21.0, or 0.21.1
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Verify network interface configurationCheck the Firecracker microVM configuration file (typically JSON) for the network interface settings. Look for the `network_interfaces` array or `iface` configuration.Affected if The microVM is configured with exactly one network interface (single NIC configuration)
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Confirm network exposure to ingress trafficReview firewall rules, security groups, or network ACLs that control inbound traffic to the Firecracker microVM. Determine if the network interface can receive external/untrusted ingress traffic.Affected if The network interface is reachable from untrusted sources and can receive incoming network traffic
You are affected if your Firecracker version is 0.20.0, 0.21.0, or 0.21.1 AND you run a microVM with a single network interface that is exposed to ingress traffic.
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 Firecracker to version 0.20.1 or 0.21.2 (or later) to patch the network stack freezing issue. Test network performance under load in a staging environment after upgrading.
- Consultation3.0 h
- Implementation2.0 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-2020-16843 — 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-2020-16843 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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