Authentication Bypass in RabbitMQ via PROXY Protocol

Publication date: 2026-07-10

Last updated on: 2026-07-10

Assigner: GitHub, Inc.

Description

RabbitMQ is a messaging and streaming broker. Prior to 3.13.15, 4.0.20, 4.1.11, and 4.2.6, AMQP 0-9-1, AMQP 1.0, and Stream Protocol authentication can allow a loopback-restricted user such as guest to connect remotely when traffic is accepted through a trusted PROXY-protocol path and the backend listener is loopback-bound because the loopback check uses the listener-side socket address instead of the real client source. This issue is fixed in versions 3.13.15, 4.0.20, 4.1.11, and 4.2.6.

CVSS Scores

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Meta Information

Published

2026-07-10

Last Modified

2026-07-10

Generated

2026-07-11

AI Q&A

2026-07-11

EPSS Evaluated

N/A

NVD

CVE-2026-57216

Affected Vendors & Products

Vendor	Product	Version / Range
rabbitmq	rabbitmq	to 3.13.15 (exc)
rabbitmq	rabbitmq	3.13.15
rabbitmq	rabbitmq	4.0.20
rabbitmq	rabbitmq	4.1.11
rabbitmq	rabbitmq	4.2.6

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-287	When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

Attack-Flow Graph

Executive Summary

This vulnerability affects RabbitMQ messaging and streaming broker versions prior to 3.13.15, 4.0.20, 4.1.11, and 4.2.6. It involves the authentication process for AMQP 0-9-1, AMQP 1.0, and Stream Protocol. Specifically, a loopback-restricted user such as 'guest' can connect remotely if the traffic is accepted through a trusted PROXY-protocol path and the backend listener is bound to the loopback interface. The issue arises because the loopback check uses the listener-side socket address instead of the actual client source address, allowing unauthorized remote connections.

Impact Analysis

This vulnerability can allow an unauthorized remote user, who should be restricted to loopback (local) access only, to connect remotely to the RabbitMQ broker. This could lead to unauthorized access to messaging services, potentially exposing sensitive data or allowing attackers to interact with the messaging system without proper permissions.

Mitigation Strategies

To mitigate this vulnerability, you should upgrade RabbitMQ to one of the fixed versions: 3.13.15, 4.0.20, 4.1.11, or 4.2.6.

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