CVE-2026-66071

What it is

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.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of service disruption.

Exploit odds

0.5% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-25 17:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-10-15 20:14 UTC Last updatedMost recent change to the record

Details

Published

2026-09-25 17:17 UTC

Last modified

2026-10-15 20:14 UTC

Exploit probability

0.5% · EPSS, next 30 days

Weakness

CWE-400 · Uncontrolled resource consumption

Record status

Analyzed

Affected

• Broadcom Rabbitmq Server < 3.13.15
• Broadcom Rabbitmq Server < 4.0.22
• Broadcom Rabbitmq Server < 4.1.11
• Broadcom Rabbitmq Server < 4.2.6
• Broadcom Rabbitmq Server < 4.3.1

Attack profile CVSS 4.0 · 6.0

Attack vector

Network

Complexity

Low

Attack requirements

Present

Privileges needed

Low

User interaction

None

Confidentiality

None

Integrity

None

Availability

High