CVE-2020-27222
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 Eclipse Californium version 2.3.0 to 2.6.0, the certificate based (x509 and RPK) DTLS handshakes accidentally fails, because the DTLS server side sticks to a wrong internal state. That wrong internal state is set by a previous certificate based DTLS handshake failure with TLS parameter mismatch. The DTLS server side must be restarted to recover this. This allow clients to force a DoS.
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 confidenceIn Eclipse Californium 2.3.0-2.6.0, the DTLS server maintains an incorrect internal state after a certificate-based (x509 or RPK) DTLS handshake failure caused by TLS parameter mismatch. This corrupted state persists across subsequent handshake attempts, causing all subsequent certificate-based DTLS handshakes to fail until the server is restarted.
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>= 2.3.0, <= 2.6.0CVSS 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.
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Identify Eclipse Californium installationLocate the Eclipse Californium library in your project dependencies (Maven pom.xml, Gradle build file, or JAR file in classpath) and note its versionAffected if The library is present and version is >= 2.3.0 and <= 2.6.0
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Verify DTLS server configurationInspect your DTLS server configuration to determine if certificate-based authentication (x509 or RPK) is enabled as the authentication methodAffected if Certificate-based (x509 or RPK) DTLS authentication is configured and the library version is in the affected range
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Check DTLS handshake behaviorMonitor DTLS handshake logs or observe network traffic for certificate-based handshake failures that persist across multiple attempts without server restartAffected if Certificate-based DTLS handshakes fail repeatedly and only succeed after server restart, indicating corrupted internal state
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Confirm version against affected rangeCompare your installed Eclipse Californium version to the affected range 2.3.0 through 2.6.0Affected if Your version falls within >= 2.3.0 and <= 2.6.0
You are affected if you are running Eclipse Californium version 2.3.0 through 2.6.0 with a DTLS server configured to use certificate-based (x509 or RPK) authentication, and you observe persistent handshake failures that clear after restart.
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 to Eclipse Californium version 2.6.1 or later, which contains the fix for proper state reset after handshake failures.
- Consultation3.0 h
- Implementation6.0 h
- Testing8.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,472.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-27222 — 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-2020-27222 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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