What is CVE-2026-67407?

CVE-2026-67407 is a high-severity vulnerability in Broadcom Rabbitmq Server, classified under Missing Authorization. CVSS score: 7.1/10. Published 2026-09-25.

How severe is CVE-2026-67407?

High severity. CVSS v3 base score is 7.1 out of 10.

Auth bypass in Broadcom Rabbitmq Server

CVE-2026-67407

RabbitMQ is a messaging and streaming broker. From 4.0.0 until 4.3.3 and 4.2.9 and 4.1.14 and 4.0.23, Incomplete fix for CVE-2026-44838: escaperegexchar/1 does not escape -, leaving room for an MQTT topic permission bypass. the CVE-2026-44838 fix made expandtopicpermission/2 escape regex metacharacters in expanded topic-permission variables (escaperegex(V)), but escaperegexchar/1 escapes \ ^ $ . | ? + ( ) [ ] { } and omits -. When a topic permission template places {clientid} inside a [...] character class A low-privileged authenticated MQTT user controlling its clientid can broaden topic authorization (read and write) when templates embed {clientid} in a [...] This issue is fixed in versions 4.3.3 and 4.2.9 and 4.1.14 and 4.0.23.

Vulnerability class: Broken Access Control

Published 2026-09-25 · last modified 2026-10-16.

CVSS v3 metric

CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (18.2th percentile), scored 2026-11-10.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 18.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000

Affected products

Broadcom Rabbitmq Server
Rabbitmq Rabbitmq-Server — versions >= 4.0.0, < 4.0.23, >= 4.1.0, < 4.1.14, >= 4.2.0, < 4.2.9

Weakness classification (CWE)

CWE-862 — Missing Authorization

References

https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-q46v-hrvq-hp24 (Exploit, Mitigation, Vendor Advisory)
https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.9 (Release Notes)
https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.3 (Release Notes)

Frequently asked questions

What is CVE-2026-67407?: CVE-2026-67407 is a high-severity vulnerability in Broadcom Rabbitmq Server, classified under Missing Authorization. CVSS score: 7.1/10. Published 2026-09-25.
How severe is CVE-2026-67407?: High severity. CVSS v3 base score is 7.1 out of 10.