RabbitMQ rabbitmq-server up to 4.2.3 Regular Expression authorization

CVSS Meta Temp Score
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CTI Interest Score
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7.0$0-$5k0.00

Summaryinfo

A vulnerability labeled as critical has been found in RabbitMQ rabbitmq-server up to 4.2.3. Impacted is an unknown function of the component Regular Expression Handler. Such manipulation leads to authorization. This vulnerability is traded as CVE-2026-44838. The attack may be launched remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in RabbitMQ rabbitmq-server up to 4.2.3 and classified as critical. Affected by this issue is an unknown part of the component Regular Expression Handler. The manipulation with an unknown input leads to a authorization vulnerability. Using CWE to declare the problem leads to CWE-863. The 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. This allows attackers to bypass intended access restrictions. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-44838 since 05/07/2026. The exploitation is known to be easy. The attack may be launched remotely. There are neither technical details nor an exploit publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 317941 (Linux Distros Unpatched Vulnerability : CVE-2026-44838), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 4.2.4 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (317941) and CERT Bund (WID-SEC-2026-1397). Once again VulDB remains the best source for vulnerability data.

Affected

  • Open Source RabbitMQ

Productinfo

Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 7.2
VulDB Meta Temp Score: 7.0

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 8.1
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Authorization
CWE: CWE-863 / CWE-285 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 317941
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-44838

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: rabbitmq-server 4.2.4

Timelineinfo

05/07/2026 CVE reserved
05/27/2026 +20 days Advisory disclosed
05/27/2026 +0 days VulDB entry created
06/07/2026 +11 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-x866-xp2g-cx8v
Status: Confirmed

CVE: CVE-2026-44838 (🔒)
GCVE (CVE): GCVE-0-2026-44838
GCVE (VulDB): GCVE-100-366404
CERT Bund: WID-SEC-2026-1397 - RabbitMQ: Mehrere Schwachstellen

Entryinfo

Created: 05/27/2026 18:56
Updated: 06/07/2026 03:19
Changes: 05/27/2026 18:56 (67), 05/28/2026 08:53 (7), 06/01/2026 14:58 (2), 06/07/2026 03:19 (11)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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