EUVD-2026-85418Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
AC:H because exploitation depends on a specific operator misconfiguration (auth class configured but failing to load); once present, any remote anonymous client gets full topic read/write, so C:H/I:H, no availability impact.
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
Lifecycle Timeline
4DescriptionCVE.org
Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, when a configured authenticator or authorizator class cannot be loaded, Server.initializeAuthenticator and Server.initializeAuthorizatorPolicy treat the failure as though no custom class was configured and fall back to AcceptAllAuthenticator or PermitAllAuthorizatorPolicy. A misspelled class name, missing dependency, constructor failure, or classpath problem can therefore start the broker with authentication or authorization disabled even though the operator configured those controls. This issue is fixed in version 0.18.1.
Articles & Coverage 1
AnalysisAI
Moquette MQTT brokers prior to 0.18.1 can start up with authentication and authorization silently disabled whenever a configured authenticator_class or authorizator_class fails to load, so any remote client - including anonymous MQTT clients, since the broker is anonymous by default - can read and write every topic the broker handles while the operator believes access controls are active. The flaw is not directly attacker-triggered: it requires a deployment that both intends to enforce auth and has a broken class-load (misspelled class name, missing dependency, constructor failure, or classpath problem), which is why the independent assessment rates it CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N even though the end-state is a full confidentiality and integrity break; the vendor's CVSS 4.0 vector is 9.3. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Not a directly attacker-triggered flaw: exploitation requires that the operator has configured a custom authenticator_class or authorizator_class in Moquette AND that class fails to load at startup (misspelled class name, missing dependency, constructor failure, or classpath problem). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The input CVSS 4.0 vector (9.3, AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N) scores this as a critical remote-unauthenticated confidentiality+integrity break, and that end-state is accurate: once the fail-open path triggers, any anonymous MQTT client reads and writes all topics. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Upgrade to Moquette 0.18.1 - vendor-released patch: 0.18.1 - which is the fix for this issue; it was introduced by PR #967 (commit 14a2f4fd280c8f6a791600c306cbccecb7c67007) and makes Server.initializeAuthenticator and Server.initializeAuthorizatorPolicy throw IllegalArgumentException and reject startup rather than silently installing AcceptAll/PermitAll, with regression test ServerAuthConfigFailClosedTest confirming both the abort behavior and that the intentional no-class default still starts. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory every Moquette-based broker in the estate, capture its exact version (anything prior to 0.18.1 is in scope), and confirm whether authentication and authorization are actually being enforced rather than assumed; review broker startup logs for authenticator_class or authorizator_class load failures, misspelled class names, or constructor exceptions, and where any doubt exists, disable the listener or isolate the broker behind network segmentation rather than leaving it exposed. …
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External POC / Exploit Code
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