CVE-2026-44838: CWE-863: Incorrect Authorization in rabbitmq rabbitmq-server
CVE-2026-44838 is a medium severity vulnerability in RabbitMQ's MQTT plugin versions 4.2.0 up to but not including 4.2.4. It involves incorrect authorization due to improper handling of user-supplied client_id values in topic-level authorization regex patterns. Because the client_id is inserted into regex patterns without escaping special characters, an authenticated MQTT user can inject regex operators to bypass topic access restrictions. This flaw is fixed in RabbitMQ versions 4.2.4 and 4.
AI Analysis
Technical Summary
RabbitMQ's MQTT plugin uses regular expressions with variable substitution to enforce topic-level authorization. From versions 4.2.0 to before 4.2.4, the client_id provided by the user in the MQTT CONNECT packet is directly inserted into the regex pattern without escaping regex special characters. This allows an authenticated user to craft a client_id containing regex operators that can bypass the intended authorization restrictions. The vulnerability is identified as CWE-863 (Incorrect Authorization). It has a CVSS 4.0 score of 5.3 (medium severity). The issue is resolved in RabbitMQ versions 4.2.4 and 4.3.0.
Potential Impact
An authenticated MQTT user can bypass topic-level authorization controls by injecting regex operators via the client_id field, potentially gaining unauthorized access to topics they should not access. This could lead to unauthorized message publication or subscription within the RabbitMQ broker. There are no known exploits in the wild as of the published date.
Mitigation Recommendations
Upgrade RabbitMQ to version 4.2.4 or later, or 4.3.0 and above, where this vulnerability is fixed. Since the vulnerability is addressed in these versions, applying the official patch is the recommended remediation. Patch status is confirmed by the vendor advisory stating the fix is included in 4.2.4 and 4.3.0. No other mitigations are indicated.
CVE-2026-44838: CWE-863: Incorrect Authorization in rabbitmq rabbitmq-server
Description
CVE-2026-44838 is a medium severity vulnerability in RabbitMQ's MQTT plugin versions 4.2.0 up to but not including 4.2.4. It involves incorrect authorization due to improper handling of user-supplied client_id values in topic-level authorization regex patterns. Because the client_id is inserted into regex patterns without escaping special characters, an authenticated MQTT user can inject regex operators to bypass topic access restrictions. This flaw is fixed in RabbitMQ versions 4.2.4 and 4.
CVSS v4.0
Score 5.3medium
Affected software
pkg:github/rabbitmq/rabbitmq-serverRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
RabbitMQ's MQTT plugin uses regular expressions with variable substitution to enforce topic-level authorization. From versions 4.2.0 to before 4.2.4, the client_id provided by the user in the MQTT CONNECT packet is directly inserted into the regex pattern without escaping regex special characters. This allows an authenticated user to craft a client_id containing regex operators that can bypass the intended authorization restrictions. The vulnerability is identified as CWE-863 (Incorrect Authorization). It has a CVSS 4.0 score of 5.3 (medium severity). The issue is resolved in RabbitMQ versions 4.2.4 and 4.3.0.
Potential Impact
An authenticated MQTT user can bypass topic-level authorization controls by injecting regex operators via the client_id field, potentially gaining unauthorized access to topics they should not access. This could lead to unauthorized message publication or subscription within the RabbitMQ broker. There are no known exploits in the wild as of the published date.
Mitigation Recommendations
Upgrade RabbitMQ to version 4.2.4 or later, or 4.3.0 and above, where this vulnerability is fixed. Since the vulnerability is addressed in these versions, applying the official patch is the recommended remediation. Patch status is confirmed by the vendor advisory stating the fix is included in 4.2.4 and 4.3.0. No other mitigations are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-07T21:21:48.352Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a170b58e29bf47b50c90700
Added to database: 05/27/2026, 15:18:48 UTC
Last enriched: 06/03/2026, 20:49:08 UTC
Last updated: 07/31/2026, 19:22:59 UTC
Views: 36
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