CVE-2025-49656 is a path traversal vulnerability (CWE-22) affecting Apache Jena, specifically versions up to 5.4.0. Apache Jena is an open-source Java framework for building Semantic Web and Linked Data applications, and Fuseki is its SPARQL server component. The vulnerability allows users with administrator privileges on the Fuseki server to create database files outside the intended restricted files directory. This improper limitation of pathname access means that an attacker with administrative access can manipulate file paths to write files arbitrarily anywhere on the server's filesystem where the Fuseki process has write permissions. This could lead to unauthorized file creation or modification, potentially overwriting critical system or application files, or planting malicious files that could be executed later. The issue arises because the server does not properly sanitize or restrict the pathname input to ensure it remains within the designated directory. The vulnerability was reserved in June 2025 and published in July 2025, with no known exploits in the wild at the time of publication. The Apache Software Foundation has addressed this issue in version 5.5.0 of Apache Jena, and users are strongly advised to upgrade to this version to mitigate the risk. No CVSS score has been assigned yet, but the vulnerability requires administrative access, limiting exploitation to trusted users or attackers who have already compromised admin credentials. However, the ability to write files outside the intended directory can have serious consequences, including data integrity compromise and potential privilege escalation if combined with other vulnerabilities.

For European organizations using Apache Jena and Fuseki servers, this vulnerability poses a significant risk to data integrity and system security. Since the exploit requires administrative access, the primary threat vector is insider misuse or attackers who have already gained elevated privileges. Successful exploitation could allow unauthorized file creation or modification, potentially leading to data corruption, service disruption, or the planting of malicious payloads that could facilitate further compromise. Organizations relying on Jena for semantic data processing, research, or linked data applications may face operational disruptions or data breaches. Given the increasing adoption of semantic web technologies in sectors like research institutions, government data portals, and enterprises across Europe, the impact could be widespread. Additionally, if attackers leverage this vulnerability in combination with other flaws, it could escalate to full system compromise. The lack of known exploits in the wild suggests limited immediate threat, but the availability of a fix means organizations should act promptly to prevent future exploitation.

The primary mitigation is to upgrade Apache Jena to version 5.5.0 or later, where this path traversal vulnerability is fixed. Beyond upgrading, organizations should implement strict access controls to limit administrative privileges on Fuseki servers to only trusted personnel. Employing file system monitoring and integrity checking tools can help detect unauthorized file creation or modification attempts outside expected directories. Additionally, running Fuseki servers with the least privileges necessary and within containerized or sandboxed environments can reduce the impact of potential exploitation. Regular audits of server configurations and logs should be conducted to identify suspicious activities. Network segmentation to isolate Fuseki servers from broader enterprise networks can further limit attacker movement if a compromise occurs. Finally, organizations should maintain an up-to-date inventory of systems running Apache Jena to ensure timely patching and vulnerability management.