CVE-2026-67418

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.

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Weakness Type (CWE)

CWE-248 CWE-248

CWE-1286 CWE-1286

References

Other References

https://github.com/rabbitmq/rabbitmq-server/commit/4639a4318c72a0660e4bc014767fad70ce288fbc https://github.com/rabbitmq/rabbitmq-server/commit/908f944a1d581d10774f8d6d0dcf2a1a713779fb https://github.com/rabbitmq/rabbitmq-server/pull/17035 https://github.com/rabbitmq/rabbitmq-server/pull/17287 https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.3.5 https://github.com/rabbitmq/rabbitmq-server/security/advisories/GHSA-jv99-v328-mvmm

Frequently Asked Questions

What is CVE-2026-67418? +

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.

How do I check if I'm vulnerable to CVE-2026-67418? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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