CVE-2026-66713 in Axis2
Summary
by MITRE • 07/28/2026
Deserialization of Untrusted Data (CWE-502) in the Tribes-based clustering component
in Apache Software Foundation Apache Axis2/Java through 2.0.0 on Apache Tomcat
(only when Tribes clustering is enabled, which is off by default) allows an
unauthenticated remote attacker with network access to the clustering port to
execute arbitrary code via a crafted serialized Java object delivered to the cluster
channel and deserialized in
org.apache.axis2.clustering.tribes.Axis2ChannelListener#messageReceived. Users are
recommended to upgrade to version 2.0.1, which fixes this issue by removing the
clustering feature entirely.
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Analysis
by VulDB Data Team • 07/28/2026
The vulnerability described represents a critical deserialization flaw classified under CWE-502, which occurs within the Tribes-based clustering component of Apache Axis2/Java versions up to 2.0.0. This weakness exists specifically when the clustering functionality is enabled on Apache Tomcat servers, though it's important to note that this feature remains disabled by default, creating a potential attack vector that requires specific configuration to exploit. The flaw manifests in the org.apache.axis2.clustering.tribes.Axis2ChannelListener#messageReceived method where incoming serialized Java objects are processed without adequate validation or sanitization measures.
The technical exploitation of this vulnerability allows unauthenticated remote attackers who possess network access to the designated clustering port to deliver maliciously crafted serialized Java objects that will be automatically deserialized by the affected system. This process creates a remote code execution (RCE) capability where attackers can execute arbitrary code on the target server with the privileges of the running Axis2/Java application. The deserialization occurs within the cluster communication channel, meaning that any object sent through this network interface could potentially trigger the malicious execution flow. This represents a classic example of insecure deserialization where the application fails to validate the integrity and contents of serialized objects before processing them.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with full control over the affected server environment. The attack requires no authentication credentials, making it particularly dangerous in environments where clustering ports are exposed to untrusted networks or where network segmentation is inadequate. Attackers can leverage this vulnerability to establish persistent access, escalate privileges, compromise additional systems within the network, and potentially use the compromised server as a launch point for further attacks. This vulnerability directly aligns with ATT&CK technique T1059.007 for command and script interpreter, as well as T1566 for malicious file delivery through serialized objects.
The recommended mitigation involves upgrading to Apache Axis2/Java version 2.0.1 or later, which completely removes the clustering feature that contains this vulnerability. This approach represents a complete remediation strategy that eliminates the attack surface entirely rather than attempting to patch the deserialization process itself. Organizations should also consider implementing network segmentation to restrict access to clustering ports, disabling the clustering functionality when not required, and monitoring for unusual network traffic patterns on cluster communication channels. Additionally, organizations should conduct thorough inventory checks to identify all systems running affected versions of Axis2/Java and ensure proper patch management procedures are in place to prevent similar vulnerabilities from being introduced through outdated software components.