---
id: CVE-2026-66071
title: RabbitMQ is a messaging and streaming broker
summary: >-
  RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.15 and
  4.0.22 and 4.1.11 and 4.2.6 and 4.3.1, Atom exhaustion: OAuth2 JWT tag: scope
  values. extractscopes/1 parses scopes of the form .tag: and calls
  rabbitdatacoercio…
severity: medium
cvss: 6
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'
cwe:
  - CWE-400
vendor: rabbitmq
product: rabbitmq-server
affected:
  - 'rabbitmq-server >= 3.13.0, < 3.13.15'
  - 'rabbitmq-server >= 4.0.0, < 4.0.22'
  - 'rabbitmq-server >= 4.1.0, < 4.1.11'
  - 'rabbitmq-server >= 4.2.0, < 4.2.6'
  - 'rabbitmq-server >= 4.3.0, < 4.3.1'
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T18:17:29.347'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-66071'
references:
  - url: >-
      https://github.com/rabbitmq/rabbitmq-server/commit/9a44124d9c932d6fc7d2a3b945e5a143e547bcb6
    label: security-advisories@github.com
  - url: >-
      https://github.com/rabbitmq/rabbitmq-server/commit/c5690583a53789a3bf00cca508b43e8246db0d11
    label: security-advisories@github.com
  - url: 'https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.6'
    label: security-advisories@github.com
  - url: 'https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.1'
    label: security-advisories@github.com
  - url: >-
      https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-89p2-f5cv-x5cg
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-25T17:53:05.694643Z'
cvssSource: cna
ingestedAt: '2026-09-25T17:13:14.028Z'
---

## Overview

RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.15 and 4.0.22 and 4.1.11 and 4.2.6 and 4.3.1, Atom exhaustion: OAuth2 JWT tag: scope values. extractscopes/1 parses scopes of the form .tag: and calls rabbitdatacoercion:toatom() to convert to a tag atom. The token signature is verified first, so the attacker cannot forge scopes , but in IdP configurations where scope content is user-influenced, each login with a novel tag value leaks one In deployments where users can influence the scopes included in their IdP-issued JWT rabbitmqauthbackendoauth2 enabled IdP permits attacker-influenced scope values in signed tokens. This issue is fixed in versions 3.13.15 and 4.0.22 and 4.1.11 and 4.2.6 and 4.3.1.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.