CVE-2026-67418: CWE-1286: Improper Validation of Syntactic Correctness of Input in rabbitmq rabbitmq-server
Description
RabbitMQ is a messaging and streaming broker. From 3.13.0 until 3.13.19, 4.0.24, 4.1.15, 4.2.10, and 4.3.5, the MQTT 5 parser in deps/rabbitmq_mqtt/src/rabbit_mqtt_packet.erl accepts Request-Problem-Information on PUBLISH packets even though the property is valid only for CONNECT. An authenticated publisher with topic write permission can cause the broker to store and route that inapplicable property to a separately authenticated matching subscriber. When the subscriber path serializes the outbound PUBLISH, serialise_prop/2 has no matching clause, and the uncontained function_clause exception closes the victim MQTT or Web MQTT connection. The publisher connection and broker remain available, and queued replay, retained-message persistence, and broker-wide denial of service were not established. This issue is fixed in versions 3.13.19, 4.0.24, 4.1.15, 4.2.10, and 4.3.5.
CVSS v4.0
Score 5.3medium
Affected software
rabbitmq
rabbitmq-server
pkg:github/rabbitmq/rabbitmq-serverRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
RabbitMQ's MQTT 5 parser in affected versions improperly validates syntactic correctness by accepting the Request-Problem-Information property on PUBLISH packets, which is only valid on CONNECT packets. This allows an authenticated publisher with topic write permission to send malformed packets that cause the broker to store and route this invalid property to subscribers. When the subscriber connection serializes the outbound PUBLISH message, the serialization function encounters an unhandled function_clause exception, resulting in the closure of the subscriber's MQTT or Web MQTT connection. The publisher connection and broker remain operational, and there is no broker-wide denial of service or message persistence issues. The vulnerability is fixed in versions 3.13.19, 4.0.24, 4.1.15, 4.2.10, and 4.3.5.
Potential Impact
An authenticated publisher with topic write permission can cause a denial of service limited to closing a subscriber's MQTT or Web MQTT connection by exploiting improper input validation in the MQTT 5 parser. The broker and publisher connections remain unaffected, and no broader denial of service or message persistence issues occur.
Mitigation Recommendations
Fixed versions are available: 3.13.19, 4.0.24, 4.1.15, 4.2.10, and 4.3.5. Users should upgrade to these versions or later to remediate this vulnerability. No other mitigation steps are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-07-29T15:02:20.412Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6acfaf362cdf04f65694d3b2
Added to database: 10/14/2026, 16:35:02 UTC
Last enriched: 10/14/2026, 16:48:52 UTC
Last updated: 10/14/2026, 19:00:29 UTC
Views: 10
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.