CVE-2026-67407 rabbitmq CVE debrief

Who should care

Defenders responsible for RabbitMQ deployments, particularly those using MQTT, should assess exposure and prioritize patching to prevent potential topic authorization bypasses. This includes verifying RabbitMQ versions and applying patches for versions 4.0.0 through 4.3.2, 4.2.8, 4.1.13, and 4.0.22. Additionally, defenders should restrict MQTT topic permissions, monitor and audit MQTT user activity, and review compensating controls for exposed systems.

Why it matters

CVE-2026-67407 is a medium-severity vulnerability in RabbitMQ that allows a low-privileged authenticated MQTT user to potentially bypass topic authorization, impacting data confidentiality and integrity. Defenders should prioritize patching and verify RabbitMQ versions to prevent exploitation.

• Potential topic authorization bypass, allowing unauthorized access to sensitive data
• Increased risk of data breaches or unauthorized modifications
• Need for verification of RabbitMQ version and patch level
• Potential impact on MQTT user authentication and authorization mechanisms

Technical summary

The incomplete fix for CVE-2026-44838 in RabbitMQ versions 4.0.0 through 4.3.2, 4.2.8, 4.1.13, and 4.0.22 allows a low-privileged authenticated MQTT user to bypass topic authorization when templates embed {clientid} in a [...] character class. This occurs because escaperegexchar/1 escapes certain regex metacharacters but omits -, enabling an MQTT topic permission bypass. The fix involves updating RabbitMQ to versions 4.3.3, 4.2.9, 4.1.14, or 4.0.23, which properly address the vulnerability. Defenders should prioritize verifying and applying these patches to prevent potential exploitation.

Defensive priority

Defenders should prioritize verifying and applying patches for RabbitMQ versions 4.0.0 through 4.3.2, 4.2.8, 4.1.13, and 4.0.22, as an authenticated MQTT user could potentially bypass topic authorization.

Recommended defensive actions

• Verify and apply patches for RabbitMQ versions 4.0.0 through 4.3.2, 4.2.8, 4.1.13, and 4.0.22
• Restrict MQTT topic permissions to minimize potential impact
• Monitor and audit MQTT user activity for suspicious behavior
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the incomplete fix for CVE-2026-44838 in RabbitMQ, allowing a low-privileged authenticated MQTT user to broaden topic authorization when templates embed {clientid} in a [...] character class.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.