What’s Vulnerable › Vulnerabilities

CVE-2026-67226: RabbitMQ: Admin-only atom exhaustion: PUT /api/users tags list

• Severity: medium (CVSS 4.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-25 · updated 2026-10-20
• Weakness: CWE-400

Description

RabbitMQ is a messaging and streaming broker. From 4.0.0 until 4.0.22 and 4.1.14 and 4.2.7, Admin-only atom exhaustion: PUT /api/users tags list. settags/2 maps rabbitdatacoercion:toatom/1 over the user's tags list. The 20 MB management body limit fits ~3-4M short tag strings. An administrator can crash the node in a single request by creating a user (or importing definitions) with ~1M unique tag administrator. This issue is fixed in versions 4.0.22 and 4.1.14 and 4.2.7.

Affected products

• rabbitmq-server: from 4.0.0 before 4.0.22; from 4.1.0 before 4.1.14; from 4.2.0 before 4.2.7 — fixed in 4.0.22, 4.1.14, 4.2.7

How to fix

Upgrade to a fixed version: rabbitmq-server 4.0.22, 4.1.14, 4.2.7. Check the vendor advisory for mitigations.

References

• https://github.com/rabbitmq/rabbitmq-server/commit/86601c5a6d1c7e41060e3dbd165c88bdc91266ee
• https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.7
• https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-34c7-r8w9-5wv8
• https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-34c7-r8w9-5wv8

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