Overview
About vulnerability
Impact
The MQTT 5 header Properties section is parsed and buffered before any message size limit is applied.
Specifically, in MqttDecoder, the decodeVariableHeader() method is called before the bytesRemainingBeforeVariableHeader > maxBytesInMessage check. The decodeVariableHeader() can call other methods which will call decodeProperties(). Effectively, Netty does not apply any limits to the size of the properties being decoded.
Additionally, because MqttDecoder extends ReplayingDecoder, Netty will repeatedly re-parse the enormous Properties sections and buffer the bytes in memory, until the entire thing parses to completion.
This can cause high resource usage in both CPU and memory.
Resources
ANT-2026-09608
https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901027
Details
- Affected product:
- Apache CXF , Apache Hadoop , Apache Kafka , Apache Log4j , Apache Solr , Apache Spark , Eclipse Jetty , Netty , Spring , Wildfly , artemis , async-http-client , aws-sdk-java , azure-sdk-for-java , bolt-connection-java , camel , cassandra-java-driver , corda , couchbase-jvm-clients , elasticsearch , flink , flink-shaded , grpc-java , grpc-netty , infinispan , java-driver , lettuce , logging-flume , neo4j-java-driver , neo4j-ogm , netty , pulsar , rabbitmq-stream-java-client , rsocket-java , tika , wildfly , zookeeper
- Affected packages:
- tika-integration-tests @ 2.9.1 (+12369 more)