In Eclipse Mosquitto version 1.6 to 2.0.10, if an authenticated client that had connected with MQTT v5 sent a crafted CONNECT message to the broker a memory leak would occur, which could be used to provide a DoS attack against the broker.

The Windows Installation component of TIBCO Software Inc.'s TIBCO Messaging - Eclipse Mosquitto Distribution - Bridge - Community Edition and TIBCO Messaging - Eclipse Mosquitto Distribution - Bridge - Enterprise Edition contains a vulnerability that theoretically allows a low privileged attacker with local access on some versions of the Windows operating system to insert malicious software. The affected component can be abused to execute the malicious software inserted by the attacker with the elevated privileges of the component. This vulnerability results from a lack of access restrictions on certain files and/or folders in the installation. Affected releases are TIBCO Software Inc.'s TIBCO Messaging - Eclipse Mosquitto Distribution - Bridge - Community Edition: versions 1.3.0 and below and TIBCO Messaging - Eclipse Mosquitto Distribution - Bridge - Enterprise Edition: versions 1.3.0 and below.

The Windows Installation component of TIBCO Software Inc.'s TIBCO Messaging - Eclipse Mosquitto Distribution - Core - Community Edition and TIBCO Messaging - Eclipse Mosquitto Distribution - Core - Enterprise Edition contains a vulnerability that theoretically allows a low privileged attacker with local access on some versions of the Windows operating system to insert malicious software. The affected component can be abused to execute the malicious software inserted by the attacker with the elevated privileges of the component. This vulnerability results from a lack of access restrictions on certain files and/or folders in the installation. Affected releases are TIBCO Software Inc.'s TIBCO Messaging - Eclipse Mosquitto Distribution - Core - Community Edition: versions 1.3.0 and below and TIBCO Messaging - Eclipse Mosquitto Distribution - Core - Enterprise Edition: versions 1.3.0 and below.

In Eclipse Mosquitto version 2.0.0 to 2.0.9, if an authenticated client that had connected with MQTT v5 sent a crafted CONNACK message to the broker, a NULL pointer dereference would occur.

In Eclipse Mosquitto 1.5.0 to 1.6.5 inclusive, if a malicious MQTT client sends a SUBSCRIBE packet containing a topic that consists of approximately 65400 or more '/' characters, i.e. the topic hierarchy separator, then a stack overflow will occur.

If an MQTT v5 client connects to Eclipse Mosquitto versions 1.6.0 to 1.6.4 inclusive, sets a last will and testament, sets a will delay interval, sets a session expiry interval, and the will delay interval is set longer than the session expiry interval, then a use after free error occurs, which has the potential to cause a crash in some situations.

In Eclipse Mosquitto version from 1.0 to 1.4.15, a Null Dereference vulnerability was found in the Mosquitto library which could lead to crashes for those applications using the library.

In Eclipse Mosquitto version 1.0 to 1.5.5 (inclusive) when a client publishes a retained message to a topic, then has its access to that topic revoked, the retained message will still be published to clients that subscribe to that topic in the future. In some applications this may result in clients being able cause effects that would otherwise not be allowed.

When Eclipse Mosquitto version 1.0 to 1.5.5 (inclusive) is configured to use an ACL file, and that ACL file is empty, or contains only comments or blank lines, then Mosquitto will treat this as though no ACL file has been defined and use a default allow policy. The new behaviour is to have an empty ACL file mean that all access is denied, which is not a useful configuration but is not unexpected.

When Eclipse Mosquitto version 1.0 to 1.5.5 (inclusive) is configured to use a password file for authentication, any malformed data in the password file will be treated as valid. This typically means that the malformed data becomes a username and no password. If this occurs, clients can circumvent authentication and get access to the broker by using the malformed username. In particular, a blank line will be treated as a valid empty username. Other security measures are unaffected. Users who have only used the mosquitto_passwd utility to create and modify their password files are unaffected by this vulnerability.