CVE-2026-44838 RabbitMQ MQTT Topic Permission Authorization Bypass
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-44838?
CVE-2026-44838 is a medium-severity vulnerability in Broadcom Rabbitmq Server, published on 27 May 2026.
Official 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.
Weakness: CWE-863
Which versions are affected by CVE-2026-44838?
1 open source package ship an affected version, including rabbitmq. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
rabbitmq Bitnami | From 4.2.0 | 4.2.4 |
Linux distribution packages (2)
rabbitmq-server4.2 Red Hat:hummingbird:1 | All versions | 0:4.2.9-0.1.hum1 |
rabbitmq-server4.3 Red Hat:hummingbird:1 | All versions | 0:4.3.4-0.1.hum1 |
Products include Broadcom Rabbitmq Server.
How do I fix CVE-2026-44838?
Upgrade rabbitmq to 4.2.4 or later.
Is CVE-2026-44838 being exploited?
There is no known exploitation of CVE-2026-44838 in the wild and no public exploit code.
Other vulnerabilities in Broadcom Rabbitmq Server
- CVE-2016-9877 Auth bypass in Pivotal RabbitMQ 3.x before 3.5.8 and 3.6.x before 3.6.6; RabbitMQ for PCF 1.5.x before 1.5.20, 1.6.x before 1.6.12 and 1.7.x before 1.7.7
- CVE-2026-67404 RabbitMQ: OAuth2 silent verify_none fallback for JWKS fetch
- CVE-2026-67231 RabbitMQ: Trust-store whitelist by Issuer+Serial only
- CVE-2026-57219 Information disclosure in rabbitmq-server
- CVE-2026-67236 RabbitMQ: Plaintext username:password stored in an insecure cookie after successful POST /login
Sources
Also known as BIT-rabbitmq-2026-44838, GHSA-x866-xp2g-cx8v, RHSA-2026:42387, RHSA-2026:45128.