CVE-2026-44838: broadcom rabbitmq_server Incorrect Authorization

Vulnerability summary

CVE-2026-44838 is a high (CVSS 8.1) Incorrect Authorization vulnerability in broadcom rabbitmq_server. EPSS estimates a 0.20% chance of exploitation in the next 30 days, higher than 9.6% of scored vulnerabilities.

Timeline

1. 27-05-2026
   PublishedVulnerability first disclosed.
2. 28-05-2026
   Last modifiedVulnerability information updated.

Description

RabbitMQ is a messaging and streaming broker. From 4.2.0 to before 4.2.4, RabbitMQ's MQTT plugin allows for topic-level authorization using regular expressions with variable substitution. Administrators can create patterns such as ^{client_id}-sensors$ to restrict user access to topics that include their client ID. However, the client_id is provided by the user in the MQTT CONNECT packet and is inserted into the regex pattern without escaping special regex characters. This flaw enables an authenticated MQTT user to inject regex operators to bypass authorization. This vulnerability is fixed in 4.2.4 and 4.3.0.

• CWE-863Incorrect AuthorizationThe product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.