# CVE-2026-67407: RabbitMQ: Incomplete fix for CVE-2026-44838: `escape_regex_char/1` does not escape `-`, leaving room for an MQTT topic permission bypass

CVE-2026-67407 is fixed in rabbitmq-server on 1 platform by DEBIAN-CVE-2026-67407 (version 4.3.6-1), released October 10, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-67407
- Priority: High
- CVSS: 7.1 (Moderate)
- EPSS: 0.0026
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 25, 2026
- Weakness: Missing Authorization
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-67407

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | rabbitmq-server Debian 14 | 4.3.6-1 | [DEBIAN-CVE-2026-67407](https://patchblox.com/security/data/fix/linux/debian-cve-2026-67407.md) | Oct 10, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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