CVE-2026-67407
Published:September 25, 2026
Updated:October 09, 2026
RabbitMQ is a messaging and streaming broker. From 4.0.0 until 4.3.3 and 4.2.9 and 4.1.14 and 4.0.23, Incomplete fix for CVE-2026-44838: escaperegexchar/1 does not escape -, leaving room for an MQTT topic permission bypass. the CVE-2026-44838 fix made expandtopicpermission/2 escape regex metacharacters in expanded topic-permission variables (escaperegex(V)), but escaperegexchar/1 escapes \ ^ $ . | ? + ( ) [ ] { } and omits -. When a topic permission template places {clientid} inside a [...] character class A low-privileged authenticated MQTT user controlling its clientid can broaden topic authorization (read and write) when templates embed {clientid} in a [...] This issue is fixed in versions 4.3.3 and 4.2.9 and 4.1.14 and 4.0.23.
Affected Packages
rabbitmq-server (CONDA):
Affected version(s) >=4.3.1 <4.3.4Fix Suggestion:
Update to version 4.3.4https://github.com/rabbitmq/rabbitmq-server.git (GITHUB):
Affected version(s) >=v4.3.0-beta.1 <v4.3.3Fix Suggestion:
Update to version v4.3.3https://github.com/rabbitmq/rabbitmq-server.git (GITHUB):
Affected version(s) >=v4.2.0-beta.1 <v4.2.9Fix Suggestion:
Update to version v4.2.9Related Resources (5)
Do you need more information?
Contact UsCVSS v4
Base Score:
5.1
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
LOW
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
NONE
Subsequent System Confidentiality
LOW
Subsequent System Integrity
HIGH
Subsequent System Availability
NONE
CVSS v3
Base Score:
8.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality
LOW
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Missing Authorization
EPSS
Base Score:
0.25