CVE-2026-44838

RabbitMQ MQTT Topic Permission Authorization Bypass

Published May 27, 2026 CVSS 4.0 · 5.3 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Broadcom
Broadcom rabbitmq Server
CPEs cpe:2.3:a:broadcom:rabbitmq_server:*:*:*:*:*:*:*:*
Vendors & Products Broadcom
Broadcom rabbitmq Server
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N'}

Type Values Removed Values Added
First Time appeared Rabbitmq
Rabbitmq rabbitmq-server
Vendors & Products Rabbitmq
Rabbitmq rabbitmq-server
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title RabbitMQ MQTT Topic Permission Authorization Bypass
Weaknesses CWE-863
References
Metrics cvssV4_0

{'score': 5.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:H/SI:H/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
May 28, 2026, 2:31 PM
Reserved
May 7, 2026, 9:21 PM
Status
Analyzed
Published
May 27, 2026, 3:16 PM
Modified
Oct 26, 2026, 11:10 AM