---
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: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-400
  - CWE-770
vendor: broadcom
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'
patched:
  - rabbitmq_server 4.3.1
published: '2026-09-25'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T20:14:57.567'
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
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-66071.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-66071'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2541515'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-66071'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-66071'
  - url: 'https://access.redhat.com/errata/RHSA-2026:67552'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00542
epssPercentile: 0.45388
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-25T17:53:05.694643Z'
scores:
  nvd: 6.5
  cna: 6
  vendor: 5.3
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.

## 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`

## Remediation

Upgrade past the affected range:

- `rabbitmq_server 4.3.1`

## Vendor advisories

- **RHSA-2026:67552** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-15 · [advisory](https://access.redhat.com/errata/RHSA-2026:67552)
- **Red Hat VEX** · Moderate · affected: Red Hat Hardened Images, Red Hat OpenStack Platform 13 (Queens), Red Hat OpenStack Platform 16.2, Red Hat OpenStack Platform 17.1, Red Hat OpenStack Platform 18.0 · no fix planned: Red Hat OpenStack Platform 13 (Queens), Red Hat OpenStack Platform 16.2, Red Hat OpenStack Platform 17.1, Red Hat Hardened Images, … · updated 2026-10-03 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-66071.json)