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Apache Camel camel-hazelcast: Unsafe Java deserialization after incomplete fix

CVE-2026-78162Critical 10.0Public exploit

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Summary

An incomplete fix for CVE-2026-43865 leaves two configuration paths of the camel-hazelcast component without the Java deserialization filter. These are ReplicatedHazelcastAggregationRepository started without a supplied hazelcastInstance, and hazelcastMode=client endpoints without a supplied ClientConfig or hazelcastConfigUri. An attacker who can publish into the affected Hazelcast cluster can send a serialized Java object that is deserialized before Camel processes the exchange, which can lead to remote code execution. Hazelcast clusters have neither authentication nor TLS enabled by default.

Affected

  • Apache Camel from 4.0.0 before 4.18.5
  • Apache Camel from 4.19.0 before 4.22.1
  • Earlier releases from 4.0.0 onward, including 4.14.x, are affected but end of life and receive no fix.
  • Deployments that upgraded only to 4.14.8, 4.18.3 or 4.21.0 for CVE-2026-43865 remain exposed.

Fixed in

  • 4.23.0
  • 4.22.1 (4.22.x stream)
  • 4.18.5 (4.18.x stream)

Workaround

  • Supply an explicit Hazelcast configuration with a JavaSerializationFilterConfig, or inject a pre-built HazelcastInstance. Camel does not overwrite user-supplied configurations.
  • Set the JVM-wide filter -Djdk.serialFilter=!java.net.;java.;javax.;org.apache.camel.;!* and enable Hazelcast cluster authentication and TLS. Verify the filter syntax against the vendor advisory before use.

Exploitation

  • CISA SSVC: exploitation status 'poc', automatable: yes, technical impact: total.
  • A public proof-of-concept repository exists on GitHub. Its contents were not reviewed.
  • No in-the-wild exploitation reported.
  • Apache rates the issue Medium; the CVE record and VulDB rate it critical (CVSS 10.0 v4.0, NVD analysis pending).

Our recommendation

  • Inventory all Camel applications that use camel-hazelcast, especially ReplicatedHazelcastAggregationRepository and hazelcastMode=client.
  • Upgrade to 4.23.0, or to 4.22.1 or 4.18.5 depending on the release line. Do not rely on the CVE-2026-43865 fix alone.
  • Until patched, restrict network access to Hazelcast ports and enable cluster authentication and TLS.
  • Plan migration away from Camel 4.14.x or earlier, which is end of life.
  • Treat the risk as high if Hazelcast traffic can reach untrusted networks.

Public exploits

Links to third-party sites, not checked by us – exploit code can contain malware. Only use it in isolated test environments.

Research sources

Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 30 Oct 2026, 14:12.

Original description (NVD)

Deserialization of Untrusted Data vulnerability in Apache Camel. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. The camel-hazelcast component applies a default Hazelcast JavaSerializationFilterConfig to the instances it creates from its own configuration, a protection introduced by CVE-2026-43865. That change did not reach two of the configuration paths Camel builds itself, so those paths continued to create Hazelcast instances whose Java deserialization is unrestricted. ReplicatedHazelcastAggregationRepository extends HazelcastAggregationRepository but overrides doStart() without calling super.doStart(), keeping its own copy of the bootstrap block, and therefore never received the filter: a route using it without supplying a hazelcastInstance starts a Hazelcast member that deserializes values read from the backing ReplicatedMap with no class restriction. HazelcastDefaultComponent#getOrCreateHzClientInstance() builds its own ClientConfig when hazelcastMode=client is selected and neither a referenced ClientConfig nor hazelcastConfigUri is supplied, and likewise applied no filter, so client-mode endpoints behaved differently from node-mode endpoints for an otherwise identical configuration. In both cases an attacker able to publish into the Hazelcast cluster that the affected instance is attached to can cause a serialized Java object of their choosing to be deserialized inside Hazelcast's own serialization layer, before Camel processes the exchange, resulting in remote code execution. Hazelcast clusters have neither authentication nor TLS enabled by default. Selecting client mode is a topology choice rather than a security option, so neither path required the deployment to opt in to unsafe behaviour. Users are recommended to upgrade to version 4.23.0, which fixes the issue. If users are on the 4.22.x releases stream, then they are suggested to upgrade to 4.22.1. If users are on the 4.18.x releases stream, then they are suggested to upgrade to 4.18.5. The 4.14.x releases stream and earlier reached end of life before this issue was resolved and will not receive a fix, so deployments on those lines must move to a supported release. For deployments that cannot upgrade immediately, supply an explicit Hazelcast configuration carrying a JavaSerializationFilterConfig, or inject a pre-built HazelcastInstance, since a user-supplied configuration is never overwritten by Camel. Alternatively set the JVM-wide filter -Djdk.serialFilter=!java.net.;java.;javax.;org.apache.camel.;!* and enable Hazelcast cluster authentication and TLS to restrict who can reach the cluster.

NVD references (8)

Sources

The tracker combines official, freely usable data sources – updated continuously:

This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.

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