CVE-2025-26866 is a vulnerability in Apache HugeGraph-Server version 1.0.0 that allows remote code execution through insecure deserialization of untrusted data within the PD store component. The root cause is the use of Hessian serialization without adequate safeguards, enabling a malicious Raft node to inject crafted serialized objects that execute arbitrary code upon deserialization. The PD store is part of the cluster coordination mechanism, and the vulnerability arises because cluster membership was not sufficiently restricted, allowing unauthorized nodes to join and exploit the deserialization flaw. The Hessian serialization process lacked a strict class whitelist, permitting dangerous object types to be deserialized. The Apache Software Foundation addressed this by enforcing IP-based authentication to restrict cluster membership to trusted nodes and implementing a strict class whitelist to harden the deserialization process against object injection attacks. The vulnerability has a CVSS v3.1 score of 8.8, reflecting its network attack vector, low attack complexity, requirement for privileges (cluster membership), no user interaction, and high impact on confidentiality, integrity, and availability. No known exploits are currently reported in the wild, but the potential for severe damage in distributed graph database environments is significant. Users are strongly advised to upgrade to version 1.7.0, which contains the fix.

For European organizations, this vulnerability poses a significant risk to any infrastructure relying on Apache HugeGraph-Server, especially in sectors such as telecommunications, finance, and government where graph databases are used for complex data relationships and analytics. Exploitation could lead to full system compromise, unauthorized data access, data manipulation, and service disruption. The ability for a malicious node to join the cluster and execute arbitrary code threatens the confidentiality and integrity of sensitive data and the availability of critical services. This could result in data breaches, operational downtime, and loss of trust. Given the distributed nature of HugeGraph clusters, lateral movement within networks is possible, amplifying the impact. Organizations with large-scale deployments or those integrating HugeGraph with other critical systems are particularly vulnerable. The lack of known exploits in the wild does not diminish the urgency due to the high severity and ease of exploitation once cluster membership is obtained.

1. Immediately upgrade all Apache HugeGraph-Server instances to version 1.7.0 or later, which includes the fix for this vulnerability. 2. Restrict cluster membership by implementing IP-based authentication or network segmentation to ensure only trusted nodes can join the cluster. 3. Review and harden network controls to limit access to the PD store ports and cluster communication channels. 4. Monitor cluster membership logs for unauthorized or suspicious node join attempts. 5. Conduct thorough audits of existing deployments to identify any unauthorized nodes or signs of exploitation. 6. Implement strict firewall rules and use VPNs or private networks for cluster communication to reduce exposure. 7. Educate DevOps and security teams about the risks of insecure deserialization and the importance of applying strict class whitelists in serialization frameworks. 8. Consider deploying runtime application self-protection (RASP) or endpoint detection and response (EDR) solutions to detect anomalous behavior indicative of exploitation attempts.