CVE-2019-11777
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 the Eclipse Paho Java client library version 1.2.0, when connecting to an MQTT server using TLS and setting a host name verifier, the result of that verification is not checked. This could allow one MQTT server to impersonate another and provide the client library with incorrect information.
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 Paho Java client library version 1.2.0, when connecting to an MQTT broker over TLS with a custom hostname verifier configured, the library fails to check the verification result. This allows a malicious MQTT server to perform a man-in-the-middle attack and impersonate legitimate servers, bypassing TLS certificate validation.
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= 1.2.0CVSS 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
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
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 Paho Java Client in dependenciesSearch your project dependencies (pom.xml, build.gradle, lib folder) for org.eclipse.paho:org.eclipse.paho.client.mqttv3 and note the versionAffected if Version is exactly 1.2.0
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Check if TLS connections are usedSearch codebase for MqttConnectOptions configured with SSL/TLS properties, such as setSSLHostnameVerifier or socket factory configurationAffected if TLS/SSL is used for MQTT connections in the application
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Identify custom hostname verifier configurationSearch for setHostnameVerifier calls on MqttConnectOptions or SSLSocketFactory setup that uses a custom hostname verifierAffected if A custom hostname verifier is configured (not using default JVM validation)
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Verify application actually connects to MQTT broker over TLSReview runtime configuration or connection code to confirm TLS/SSL port (typically 8883) or wss:// URI scheme is usedAffected if Application connects to MQTT broker using TLS
Affected if Eclipse Paho Java Client version 1.2.0 is used AND TLS connections are established with a custom hostname verifier, as the library fails to check the verification result in this configuration.
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 Eclipse Paho Java client to version 1.2.1 or later where the hostname verification result is properly checked. Alternatively, validate TLS certificate chain through underlying JVM trust stores as a defense-in-depth measure.
- Consultation2.0 h
- Implementation1.0 h
- Testing4.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-11777 — 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-2019-11777 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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