CVE-2026-44838: 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…

PriorityP353high8.1CVSS 3.1

AVNACLPRLUINSUCHIHAN

EPSS

0.25%

16.3th percentile

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.

Affected

2 ranges

Vendor	Product	Version range	Fixed in
broadcom	rabbitmq_server	>= 4.2.0 < 4.2.4	4.2.4
rabbitmq	rabbitmq-server	—	—

CVSS provenance

nvdv3.18.1HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

nvdv4.05.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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