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.

Several issues have been found in mosquitto, a MQTT version 3.1/3.1.1 compatible message broker.

CVE-2017-7655

A Null dereference vulnerability in the Mosquitto library could lead to crashes for those applications using the library.

CVE-2018-12550

An ACL file with no statements was treated as having a default allow policy. The new behaviour of an empty ACL file is a default policy of access denied. (this is in compliance with all newer releases)

CVE-2018-12551

Malformed authentication data in the password file could allow clients to circumvent authentication and get access to the broker.

CVE-2019-11779

Fix for processing a crafted SUBSCRIBE packet containing a topic that consists of approximately 65400 or more '/' characters. (setting TOPIC_HIERARCHY_LIMIT to 200)

For Debian 8 'Jessie', these problems have been fixed in version 1.3.4-2+deb8u4.

We recommend that you upgrade your mosquitto packages.

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

This update for mosquitto fixes the following issues :

Security issues fixed :

  - CVE-2018-12546: Fixed an issue with revoked access to     topics (bsc#1125019).

  - CVE-2018-12551: Fixed an issue which allowed malformed     data in the password file to be treated as valid     (bsc#1125020).

  - CVE-2018-12550: Fixed an an issue which treats an empty     ACL file wrongly (bsc#1125021).

Fixes for the following CVES :

  - CVE-2018-12546

  - CVE-2018-12550

  - CVE-2018-12551 

The list of other fixes addressed in version 1.5.6 is: Broker :

  - Fixed comment handling for config options that have     optional arguments.

  - Improved documentation around bridge topic remapping.

  - Handle mismatched handshakes (e.g. QoS1 PUBLISH with     QoS2 reply) properly.

  - Fix spaces not being allowed in the bridge     remote_username option. Closes #1131.

  - Allow broker to always restart on Windows when using     log_dest file. Closes #1080.

  - Fix Will not being sent for Websockets clients. Closes     #1143.

  - Windows: Fix possible crash when client disconnects.
    Closes #1137.

  - Fixed durable clients being unable to receive messages     when offline, when per_listener_settings was set to     true. Closes #1081.

  - Add log message for the case where a client is     disconnected for sending a topic with invalid UTF-8.
    Closes #1144.

Library :

  - Fix TLS connections not working over SOCKS.

  - Don't clear SSL context when TLS connection is closed,     meaning if a user provided an external SSL_CTX they have     less chance of leaking references.

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website.
Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Three vulnerabilities were discovered in the Mosquitto MQTT broker, which could result in authentication bypass. Please refer to https://mosquitto.org/blog/2019/02/version-1-5-6-released/ for additional information.

ID	Name	Product	Family	Severity
130285	Debian DLA-1972-1 : mosquitto security update	Nessus	Debian Local Security Checks	high
122417	openSUSE Security Update : mosquitto (openSUSE-2019-233)	Nessus	SuSE Local Security Checks	high
122285	Fedora 28 : mosquitto (2019-8cbe2a05cd)	Nessus	Fedora Local Security Checks	high
122069	Debian DSA-4388-1 : mosquitto - security update	Nessus	Debian Local Security Checks	high

Detections

Analytics

CVE-2018-12550

high

Tenable Plugins

high

high

high

high