CVE-2026-43865: Apache Camel: Camel-Hazelcast: Unsafe Java deserialization in default-configured managed Hazelcast instances enables remote code execution

[Andrea Cosentino <acosentino () apache org>]

Severity: moderate 

Affected versions:

- Apache Camel (org.apache.camel:camel-hazelcast) 4.0.0 before 4.14.8
- Apache Camel (org.apache.camel:camel-hazelcast) 4.15.0 before 4.18.3
- Apache Camel (org.apache.camel:camel-hazelcast) 4.19.0 before 4.21.0

Description:

Deserialization of Untrusted Data vulnerability in Apache Camel Hazelcast component.

The camel-hazelcast component creates and manages Hazelcast instances using a default configuration that applies no 
Java deserialization filter. When Camel builds the Hazelcast Config itself - that is, when no user-supplied 
HazelcastInstance, hazelcastConfigUri, or referenced Config bean is provided - neither Hazelcast's 
JavaSerializationFilterConfig nor a Camel-side ObjectInputFilter is configured, so objects received over the Hazelcast 
cluster protocol are deserialized inside Hazelcast's own serialization layer (ObjectInputStream.readObject) before 
Camel ever processes them. An attacker who can join or otherwise reach the Hazelcast cluster can publish a crafted 
serialized Java object that is then deserialized on every Camel node, resulting in remote code execution. The exposure 
is present by default and requires no opt-in endpoint configuration: any route using a hazelcast consumer 
(hazelcast-topic, hazelcast-queue, hazelcast-seda, hazelcast-map, hazelcast-multimap, hazelcast-replicatedmap, 
hazelcast-list, hazelcast-set), as well as the HazelcastAggregationRepository and HazelcastIdempotentRepository, is 
affected whenever the managed instance is created from Camel's default configuration.
This issue affects Apache Camel: from 4.0.0 before 4.14.8, from 4.15.0 before 4.18.3, from 4.19.0 before 4.21.0.

Users are recommended to upgrade to version 4.21.0, which fixes the issue. If users are on the 4.14.x LTS releases 
stream, then they are suggested to upgrade to 4.14.8. If users are on the 4.18.x releases stream, then they are 
suggested to upgrade to 4.18.3. The fix makes Camel apply a default Hazelcast JavaSerializationFilterConfig 
(whitelisting the java., javax. and org.apache.camel. class-name prefixes and blacklisting java.net.) to instances it 
creates from its own default configuration, while leaving any user-supplied Config or HazelcastInstance untouched. For 
deployments that cannot upgrade immediately, configure a deserialization filter on the Hazelcast instance (Hazelcast 
JavaSerializationFilterConfig, or the JVM-wide system property 
-Djdk.serialFilter=!java.net.**;java.**;javax.**;org.apache.camel.**;!*) and enable Hazelcast cluster authentication 
and TLS to restrict who can reach the cluster.

Credit:

gaorenyusi (finder)

References:

https://camel.apache.org/security/CVE-2026-43865.html
https://camel.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-43865