Quick answer
Direct answer
Risk scores
| CVSS metric | What it means |
|---|---|
| Attack vector (AV:N) | Network: reachable remotely |
| Attack complexity (AC:L) | Low complexity |
| Attack requirements (AT:N) | No attack requirements |
| Privileges required (PR:N) | No privileges required |
| User interaction (UI:N) | No user interaction |
| Confidentiality (VC:N) | No confidentiality impact |
| Integrity (VI:H) | High integrity impact |
| Availability (VA:N) | No availability impact |
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/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
About Moquette
CVE-2026-95846 affects Moquette, a product from Moquette. Before acting, confirm where Moquette runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.
What the flaw is
In plain terms: Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, PostOffice.publishWill publishes a client's Last-Will message without applying the canWrite authorization and reserved-topic checks used for a normal PUBLISH. A client can configure a Will for a topic that the client is not permitted to write and cause the broker to publish the unauthorized message when the client disconnects unexpectedly. This issue allows unauthorized message injection into restricted topics. This issue is fixed in version 0.18.1.
The weakness class is Missing Authorization. The software does not check permissions before an action.
Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Affected versions and timeline
| Field | Detail |
|---|---|
| Product | Moquette |
| Affected versions | Moquette before 0.18.1 |
| Published | Sep 23, 2026 |
| Last modified | Sep 25, 2026 |
| Added to CISA KEV | Not listed |
| Assigning CNA | security-advisories@github.com |
How to detect it
- Inventory every instance of Moquette and record the running version against the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
- Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.
How to fix it
- Apply the fixed version of Moquette named in the vendor advisory.
- If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
- Rescan after the change to prove the exposure is gone, then close the ticket.
CTEM action plan
| CTEM stage | What to do for this CVE |
|---|---|
| Scope | Add every business service that depends on Moquette to the current CTEM cycle. |
| Discover | Find all instances, including shadow and cloud deployments, and record versions and exposure. |
| Prioritize | Rank using EPSS and CVSS together with asset exposure and business impact. |
| Validate | Confirm the flaw is reachable and exploitable in your environment and that compensating controls work. |
| Mobilize | Assign the fix to the asset owner with a due date matched to the priority, then verify closure. |
CWE References
- CWE-862: Missing Authorization More CVEs with this weakness
Technical References
Frequently asked questions
Related CVEs
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.
Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, H2PersistentQueue derives a session's message-map name as queue_ plus the client ID and its metadata-map name as queue_ plus the client ID plus _meta. A durable session whose client ID ends in _meta can therefore make its message map collide with another client's metadata map. The colliding sessions read and write the same H2 MVStore map with incompatible value types, which can corrupt queue head and tail data and cause message loss, misdelivery, failed queue reloads, or exposure of queued content across sessions. This issue is fixed in version 0.18.1.
Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, the broker does not enforce a maximum length for pending per-session message queues. When a fast publisher sends messages to a slow subscriber whose in-flight window is full, queued messages can accumulate without bound in memory or persistent storage. Remote clients can use this condition to exhaust broker resources and cause a denial of service. This issue is fixed in version 0.18.1.
Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, Moquette does not limit the depth of topic names and topic filters before processing them through recursive CTrie insertion and matching operations. A remote client can publish or subscribe with a deeply nested topic, causing a StackOverflowError that disrupts session processing and can deny service to broker clients. This issue is fixed in version 0.18.1.
Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, PostOffice.subscribe parses a shared-subscription filter through SharedSubscriptionUtils.extractShareName before validating the complete $share/{shareName}/{topicFilter} structure. A remote client can send a filter such as $share/grp without a topic-filter portion, causing a StringIndexOutOfBoundsException while calculating the share name. The exception terminates command handling on the shared session event loop and can deny service to other client sessions assigned to that loop. This issue is fixed in version 0.18.1.
Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, SessionEventLoop.run catches only InterruptedException, and SessionEventLoopGroup does not restart a terminated loop. An MQTT command that raises an uncaught exception can terminate an event loop shared by multiple client sessions, preventing every co-located client from processing PUBLISH, SUBSCRIBE, PUBACK, and other commands. An attacker can select client IDs that map across the available loops to disrupt session processing for the entire broker. This issue is fixed in version 0.18.1.
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